diff --git a/src/backend/distributed/executor/multi_executor.c b/src/backend/distributed/executor/multi_executor.c
index 9d2a8ea61..061f00619 100644
--- a/src/backend/distributed/executor/multi_executor.c
+++ b/src/backend/distributed/executor/multi_executor.c
@@ -52,6 +52,9 @@ multi_ExecutorStart(QueryDesc *queryDesc, int eflags)
 		MultiExecutorType executorType = MULTI_EXECUTOR_INVALID_FIRST;
 		Job *workerJob = multiPlan->workerJob;
 
+		/* ensure plan is executable */
+		VerifyMultiPlanValidity(multiPlan);
+
 		ExecCheckRTPerms(planStatement->rtable, true);
 
 		executorType = JobExecutorType(multiPlan);
diff --git a/src/backend/distributed/planner/multi_explain.c b/src/backend/distributed/planner/multi_explain.c
index fd4f59cef..46d410c90 100644
--- a/src/backend/distributed/planner/multi_explain.c
+++ b/src/backend/distributed/planner/multi_explain.c
@@ -167,6 +167,9 @@ MultiExplainOnePlan(PlannedStmt *plan, IntoClause *into,
 
 	multiPlan = GetMultiPlan(plan);
 
+	/* ensure plan is executable */
+	VerifyMultiPlanValidity(multiPlan);
+
 	if (!ExplainDistributedQueries)
 	{
 		appendStringInfo(es->str, "explain statements for distributed queries ");
diff --git a/src/backend/distributed/planner/multi_planner.c b/src/backend/distributed/planner/multi_planner.c
index 28a77fe77..ca8ea5769 100644
--- a/src/backend/distributed/planner/multi_planner.c
+++ b/src/backend/distributed/planner/multi_planner.c
@@ -25,6 +25,7 @@
 #include "executor/executor.h"
 
 #include "nodes/makefuncs.h"
+#include "nodes/nodeFuncs.h"
 
 #include "optimizer/planner.h"
 
@@ -42,11 +43,13 @@ static PlannedStmt * MultiQueryContainerNode(PlannedStmt *result,
 static struct PlannedStmt * CreateDistributedPlan(PlannedStmt *localPlan,
 												  Query *originalQuery,
 												  Query *query,
+												  ParamListInfo boundParams,
 												  RelationRestrictionContext *
 												  restrictionContext);
 static RelationRestrictionContext * CreateAndPushRestrictionContext(void);
 static RelationRestrictionContext * CurrentRestrictionContext(void);
 static void PopRestrictionContext(void);
+static bool HasUnresolvedExternParamsWalker(Node *expression, ParamListInfo boundParams);
 
 
 /* Distributed planner hook */
@@ -103,7 +106,7 @@ multi_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
 		if (needsDistributedPlanning)
 		{
 			result = CreateDistributedPlan(result, originalQuery, parse,
-										   restrictionContext);
+										   boundParams, restrictionContext);
 		}
 	}
 	PG_CATCH();
@@ -139,29 +142,49 @@ IsModifyCommand(Query *query)
 }
 
 
+/*
+ * VerifyMultiPlanValidity verifies that multiPlan is ready for execution, or
+ * errors out if not.
+ *
+ * A plan may e.g. not be ready for execution because CreateDistributedPlan()
+ * couldn't find a plan due to unresolved prepared statement parameters, but
+ * didn't error out, because we expect custom plans to come to our rescue.
+ * But sql (not plpgsql) functions unfortunately don't go through a codepath
+ * supporting custom plans.
+ */
+void
+VerifyMultiPlanValidity(MultiPlan *multiPlan)
+{
+	if (multiPlan->planningError)
+	{
+		RaiseDeferredError(multiPlan->planningError, ERROR);
+	}
+}
+
+
 /*
  * CreateDistributedPlan encapsulates the logic needed to transform a particular
  * query into a distributed plan.
  */
 static PlannedStmt *
 CreateDistributedPlan(PlannedStmt *localPlan, Query *originalQuery, Query *query,
+					  ParamListInfo boundParams,
 					  RelationRestrictionContext *restrictionContext)
 {
 	MultiPlan *distributedPlan = NULL;
+	PlannedStmt *resultPlan = NULL;
+	bool hasUnresolvedParams = false;
+
+	if (HasUnresolvedExternParamsWalker((Node *) query, boundParams))
+	{
+		hasUnresolvedParams = true;
+	}
 
 	if (IsModifyCommand(query))
 	{
-		/*
-		 * Modifications are always routed through the same
-		 * planner/executor. As there's currently no other way to plan these,
-		 * error out if the query is unsupported.
-		 */
+		/* modifications are always routed through the same planner/executor */
 		distributedPlan = CreateModifyPlan(originalQuery, query, restrictionContext);
 		Assert(distributedPlan);
-		if (distributedPlan->planningError)
-		{
-			RaiseDeferredError(distributedPlan->planningError, ERROR);
-		}
 	}
 	else
 	{
@@ -182,8 +205,13 @@ CreateDistributedPlan(PlannedStmt *localPlan, Query *originalQuery, Query *query
 			}
 		}
 
-		/* router didn't yield a plan, try the full distributed planner */
-		if (!distributedPlan || distributedPlan->planningError)
+		/*
+		 * Router didn't yield a plan, try the full distributed planner. As
+		 * real-time/task-tracker don't support prepared statement parameters,
+		 * skip planning in that case (we'll later trigger an error in that
+		 * case if necessary).
+		 */
+		if ((!distributedPlan || distributedPlan->planningError) && !hasUnresolvedParams)
 		{
 			/* Create and optimize logical plan */
 			MultiTreeRoot *logicalPlan = MultiLogicalPlanCreate(query);
@@ -206,8 +234,62 @@ CreateDistributedPlan(PlannedStmt *localPlan, Query *originalQuery, Query *query
 		}
 	}
 
+	/*
+	 * If no plan was generated, prepare a generic error to be emitted.
+	 * Normally this error message will never returned to the user, as it's
+	 * usually due to unresolved prepared statement parameters - in that case
+	 * the logic below will force a custom plan (i.e. with parameters bound to
+	 * specific values) to be generated.  But sql (not plpgsql) functions
+	 * unfortunately don't go through a codepath supporting custom plans - so
+	 * we still need to have an error prepared.
+	 */
+	if (!distributedPlan)
+	{
+		/* currently always should have a more specific error otherwise */
+		Assert(hasUnresolvedParams);
+		distributedPlan = CitusMakeNode(MultiPlan);
+		distributedPlan->planningError =
+			DeferredError(ERRCODE_FEATURE_NOT_SUPPORTED,
+						  "could not create distributed plan",
+						  "Possibly this is caused by the use of parameters in SQL "
+						  "functions, which is not supported in Citus.",
+						  "Consider using PLPGSQL functions instead.");
+	}
+
+	/*
+	 * Error out if none of the planners resulted in a usable plan, unless the
+	 * error was possibly triggered by missing parameters.  In that case we'll
+	 * not error out here, but instead rely on postgres' custom plan logic.
+	 * Postgres re-plans prepared statements the first five executions
+	 * (i.e. it produces custom plans), after that the cost of a generic plan
+	 * is compared with the average custom plan cost.  We support otherwise
+	 * unsupported prepared statement parameters by assigning an exorbitant
+	 * cost to the unsupported query.  That'll lead to the custom plan being
+	 * chosen.  But for that to be possible we can't error out here, as
+	 * otherwise that logic is never reached.
+	 */
+	if (distributedPlan->planningError && !hasUnresolvedParams)
+	{
+		RaiseDeferredError(distributedPlan->planningError, ERROR);
+	}
+
 	/* store required data into the planned statement */
-	return MultiQueryContainerNode(localPlan, distributedPlan);
+	resultPlan = MultiQueryContainerNode(localPlan, distributedPlan);
+
+	/*
+	 * As explained above, force planning costs to be unrealistically high if
+	 * query planning failed (possibly) due to prepared statement parameters.
+	 */
+	if (distributedPlan->planningError && hasUnresolvedParams)
+	{
+		/*
+		 * Arbitraryly high cost, but low enough that it can be added up
+		 * without overflowing by choose_custom_plan().
+		 */
+		resultPlan->planTree->total_cost = FLT_MAX / 100000000;
+	}
+
+	return resultPlan;
 }
 
 
@@ -502,3 +584,70 @@ PopRestrictionContext(void)
 {
 	relationRestrictionContextList = list_delete_first(relationRestrictionContextList);
 }
+
+
+/*
+ * HasUnresolvedExternParamsWalker returns true if the passed in expression
+ * has external parameters that are not contained in boundParams, false
+ * otherwise.
+ */
+static bool
+HasUnresolvedExternParamsWalker(Node *expression, ParamListInfo boundParams)
+{
+	if (expression == NULL)
+	{
+		return false;
+	}
+
+	if (IsA(expression, Param))
+	{
+		Param *param = (Param *) expression;
+		int paramId = param->paramid;
+
+		/* only care about user supplied parameters */
+		if (param->paramkind != PARAM_EXTERN)
+		{
+			return false;
+		}
+
+		/* don't care about our special parameter, it'll be removed during planning */
+		if (paramId == UNINSTANTIATED_PARAMETER_ID)
+		{
+			return false;
+		}
+
+		/* check whether parameter is available (and valid) */
+		if (boundParams && paramId > 0 && paramId <= boundParams->numParams)
+		{
+			ParamExternData *externParam = &boundParams->params[paramId - 1];
+
+			/* give hook a chance in case parameter is dynamic */
+			if (!OidIsValid(externParam->ptype) && boundParams->paramFetch != NULL)
+			{
+				(*boundParams->paramFetch)(boundParams, paramId);
+			}
+
+			if (OidIsValid(externParam->ptype))
+			{
+				return false;
+			}
+		}
+
+		return true;
+	}
+
+	/* keep traversing */
+	if (IsA(expression, Query))
+	{
+		return query_tree_walker((Query *) expression,
+								 HasUnresolvedExternParamsWalker,
+								 boundParams,
+								 0);
+	}
+	else
+	{
+		return expression_tree_walker(expression,
+									  HasUnresolvedExternParamsWalker,
+									  boundParams);
+	}
+}
diff --git a/src/include/distributed/multi_planner.h b/src/include/distributed/multi_planner.h
index baee8a064..1c1d7a337 100644
--- a/src/include/distributed/multi_planner.h
+++ b/src/include/distributed/multi_planner.h
@@ -57,5 +57,6 @@ extern struct MultiPlan * GetMultiPlan(PlannedStmt *planStatement);
 extern void multi_relation_restriction_hook(PlannerInfo *root, RelOptInfo *relOptInfo,
 											Index index, RangeTblEntry *rte);
 extern bool IsModifyCommand(Query *query);
+extern void VerifyMultiPlanValidity(struct MultiPlan *multiPlan);
 
 #endif /* MULTI_PLANNER_H */
diff --git a/src/test/regress/expected/multi_explain.out b/src/test/regress/expected/multi_explain.out
index a71965210..bafe813bb 100644
--- a/src/test/regress/expected/multi_explain.out
+++ b/src/test/regress/expected/multi_explain.out
@@ -727,3 +727,10 @@ Distributed Query into pg_merge_job_570039
 Master Query
   ->  Aggregate
         ->  Seq Scan on pg_merge_job_570039
+-- EXPLAIN EXECUTE of parametrized prepared statements is broken, but
+-- at least make sure to fail without crashing
+PREPARE router_executor_query_param(int) AS SELECT l_quantity FROM lineitem WHERE l_orderkey = $1;
+EXPLAIN EXECUTE router_executor_query_param(5);
+ERROR:  could not create distributed plan
+DETAIL:  Possibly this is caused by the use of parameters in SQL functions, which is not supported in Citus.
+HINT:  Consider using PLPGSQL functions instead.
diff --git a/src/test/regress/expected/multi_explain_0.out b/src/test/regress/expected/multi_explain_0.out
index 9e414231e..7425b80e3 100644
--- a/src/test/regress/expected/multi_explain_0.out
+++ b/src/test/regress/expected/multi_explain_0.out
@@ -698,3 +698,10 @@ Distributed Query into pg_merge_job_570039
 Master Query
   ->  Aggregate
         ->  Seq Scan on pg_merge_job_570039
+-- EXPLAIN EXECUTE of parametrized prepared statements is broken, but
+-- at least make sure to fail without crashing
+PREPARE router_executor_query_param(int) AS SELECT l_quantity FROM lineitem WHERE l_orderkey = $1;
+EXPLAIN EXECUTE router_executor_query_param(5);
+ERROR:  could not create distributed plan
+DETAIL:  Possibly this is caused by the use of parameters in SQL functions, which is not supported in Citus.
+HINT:  Consider using PLPGSQL functions instead.
diff --git a/src/test/regress/expected/multi_prepare_plsql.out b/src/test/regress/expected/multi_prepare_plsql.out
index 3490beed7..837ab4c2d 100644
--- a/src/test/regress/expected/multi_prepare_plsql.out
+++ b/src/test/regress/expected/multi_prepare_plsql.out
@@ -265,9 +265,18 @@ SELECT plpgsql_test_2();
 (1 row)
 
 -- run PL/pgsql functions with different parameters
--- FIXME: temporarily disabled, waiting for proper parametrized query support
--- SELECT plpgsql_test_6(155);
--- SELECT plpgsql_test_6(1555);
+SELECT plpgsql_test_6(155);
+ plpgsql_test_6 
+----------------
+          11811
+(1 row)
+
+SELECT plpgsql_test_6(1555);
+ plpgsql_test_6 
+----------------
+          10183
+(1 row)
+
 -- test router executor parameterized PL/pgsql functions
 CREATE TABLE plpgsql_table (
 	key int,
@@ -365,9 +374,11 @@ SELECT single_parameter_insert(5);
 (1 row)
 
 SELECT single_parameter_insert(6);
-ERROR:  values given for the partition column must be constants or constant expressions
-CONTEXT:  SQL statement "INSERT INTO plpgsql_table (key) VALUES (key_arg)"
-PL/pgSQL function single_parameter_insert(integer) line 3 at SQL statement
+ single_parameter_insert 
+-------------------------
+ 
+(1 row)
+
 CREATE FUNCTION double_parameter_insert(key_arg int, value_arg int)
 	RETURNS void as $$
 BEGIN
@@ -406,9 +417,11 @@ SELECT double_parameter_insert(5, 50);
 (1 row)
 
 SELECT double_parameter_insert(6, 60);
-ERROR:  values given for the partition column must be constants or constant expressions
-CONTEXT:  SQL statement "INSERT INTO plpgsql_table (key, value) VALUES (key_arg, value_arg)"
-PL/pgSQL function double_parameter_insert(integer,integer) line 3 at SQL statement
+ double_parameter_insert 
+-------------------------
+ 
+(1 row)
+
 CREATE FUNCTION non_partition_parameter_insert(value_arg int)
 	RETURNS void as $$
 BEGIN
@@ -478,7 +491,9 @@ SELECT * FROM plpgsql_table ORDER BY key, value;
    4 |      
    5 |    50
    5 |      
-(22 rows)
+   6 |    60
+   6 |      
+(24 rows)
 
 -- check router executor select
 CREATE FUNCTION router_partition_column_select(key_arg int)
@@ -498,6 +513,7 @@ BEGIN
 		value;
 END;
 $$ LANGUAGE plpgsql;
+-- execute 6 times to trigger prepared statement usage
 SELECT router_partition_column_select(1);
  router_partition_column_select 
 --------------------------------
@@ -533,9 +549,13 @@ SELECT router_partition_column_select(5);
  (5,)
 (2 rows)
 
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- SELECT router_partition_column_select(6);
+SELECT router_partition_column_select(6);
+ router_partition_column_select 
+--------------------------------
+ (6,60)
+ (6,)
+(2 rows)
+
 CREATE FUNCTION router_non_partition_column_select(value_arg int)
 	RETURNS TABLE(key int, value int) AS $$
 DECLARE
@@ -554,6 +574,7 @@ BEGIN
 		value;
 END;
 $$ LANGUAGE plpgsql;
+-- execute 6 times to trigger prepared statement usage
 SELECT router_non_partition_column_select(10);
  router_non_partition_column_select 
 ------------------------------------
@@ -608,6 +629,7 @@ BEGIN
 		value;
 END;
 $$ LANGUAGE plpgsql;
+-- execute 6 times to trigger prepared statement usage
 SELECT real_time_non_partition_column_select(10);
  real_time_non_partition_column_select 
 ---------------------------------------
@@ -643,9 +665,13 @@ SELECT real_time_non_partition_column_select(50);
  (5,50)
 (2 rows)
 
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- SELECT real_time_non_partition_column_select(60);
+SELECT real_time_non_partition_column_select(60);
+ real_time_non_partition_column_select 
+---------------------------------------
+ (0,60)
+ (6,60)
+(2 rows)
+
 CREATE FUNCTION real_time_partition_column_select(key_arg int)
 	RETURNS TABLE(key int, value int) AS $$
 DECLARE
@@ -664,6 +690,7 @@ BEGIN
 		value;
 END;
 $$ LANGUAGE plpgsql;
+-- execute 6 times to trigger prepared statement usage
 SELECT real_time_partition_column_select(1);
  real_time_partition_column_select 
 -----------------------------------
@@ -708,9 +735,15 @@ SELECT real_time_partition_column_select(5);
  (5,)
 (4 rows)
 
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- SELECT real_time_partition_column_select(6);
+SELECT real_time_partition_column_select(6);
+ real_time_partition_column_select 
+-----------------------------------
+ (0,10)
+ (1,10)
+ (6,60)
+ (6,)
+(4 rows)
+
 -- check task-tracker executor
 SET citus.task_executor_type TO 'task-tracker';
 CREATE FUNCTION task_tracker_non_partition_column_select(value_arg int)
@@ -730,6 +763,7 @@ BEGIN
 		value;
 END;
 $$ LANGUAGE plpgsql;
+-- execute 6 times to trigger prepared statement usage
 SELECT task_tracker_non_partition_column_select(10);
  task_tracker_non_partition_column_select 
 ------------------------------------------
@@ -765,9 +799,13 @@ SELECT task_tracker_non_partition_column_select(50);
  (5,50)
 (2 rows)
 
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- SELECT real_time_non_partition_column_select(60);
+SELECT real_time_non_partition_column_select(60);
+ real_time_non_partition_column_select 
+---------------------------------------
+ (0,60)
+ (6,60)
+(2 rows)
+
 CREATE FUNCTION task_tracker_partition_column_select(key_arg int)
 	RETURNS TABLE(key int, value int) AS $$
 DECLARE
@@ -786,6 +824,7 @@ BEGIN
 		value;
 END;
 $$ LANGUAGE plpgsql;
+-- execute 6 times to trigger prepared statement usage
 SELECT task_tracker_partition_column_select(1);
  task_tracker_partition_column_select 
 --------------------------------------
@@ -830,9 +869,15 @@ SELECT task_tracker_partition_column_select(5);
  (5,)
 (4 rows)
 
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- SELECT task_tracker_partition_column_select(6);
+SELECT task_tracker_partition_column_select(6);
+ task_tracker_partition_column_select 
+--------------------------------------
+ (0,10)
+ (1,10)
+ (6,60)
+ (6,)
+(4 rows)
+
 SET citus.task_executor_type TO 'real-time';
 -- check updates
 CREATE FUNCTION partition_parameter_update(int, int) RETURNS void as $$
@@ -871,8 +916,7 @@ SELECT partition_parameter_update(5, 51);
  
 (1 row)
 
--- This fails with an unexpected error message
-SELECT partition_parameter_update(5, 52);
+SELECT partition_parameter_update(6, 61);
 ERROR:  distributed modifications must target exactly one shard
 DETAIL:  This command modifies all shards.
 HINT:  Consider using an equality filter on partition column "key". You can use master_modify_multiple_shards() to perform multi-shard delete or update operations.
@@ -946,7 +990,9 @@ SELECT * FROM plpgsql_table ORDER BY key, value;
    4 |    41
    5 |    51
    5 |    51
-(22 rows)
+   6 |    60
+   6 |      
+(24 rows)
 
 -- check deletes
 CREATE FUNCTION partition_parameter_delete(int, int) RETURNS void as $$
@@ -954,6 +1000,7 @@ BEGIN
 	DELETE FROM plpgsql_table WHERE key = $1 AND value = $2;
 END;
 $$ LANGUAGE plpgsql;
+-- execute 6 times to trigger prepared statement usage
 SELECT partition_parameter_delete(1, 11);
  partition_parameter_delete 
 ----------------------------
@@ -984,8 +1031,7 @@ SELECT partition_parameter_delete(5, 51);
  
 (1 row)
 
--- This fails with an unexpected error message
-SELECT partition_parameter_delete(0, 10);
+SELECT partition_parameter_delete(6, 61);
 ERROR:  distributed modifications must target exactly one shard
 DETAIL:  This command modifies all shards.
 HINT:  Consider using an equality filter on partition column "key". You can use master_modify_multiple_shards() to perform multi-shard delete or update operations.
@@ -1043,7 +1089,9 @@ SELECT * FROM plpgsql_table ORDER BY key, value;
    0 |      
    0 |      
    0 |      
-(6 rows)
+   6 |    60
+   6 |      
+(8 rows)
 
 -- check whether we can handle execute parameters
 CREATE TABLE execute_parameter_test (key int, val date);
diff --git a/src/test/regress/expected/multi_prepare_sql.out b/src/test/regress/expected/multi_prepare_sql.out
index 5bac00df5..8f7e7424d 100644
--- a/src/test/regress/expected/multi_prepare_sql.out
+++ b/src/test/regress/expected/multi_prepare_sql.out
@@ -240,8 +240,12 @@ EXECUTE prepared_test_6(155);
  11811
 (1 row)
 
--- FIXME: temporarily disabled
--- EXECUTE prepared_test_6(1555);
+EXECUTE prepared_test_6(1555);
+ count 
+-------
+ 10183
+(1 row)
+
 -- test router executor with parameterized non-partition columns
 -- create a custom type which also exists on worker nodes
 CREATE TYPE test_composite_type AS (
@@ -325,17 +329,16 @@ EXECUTE prepared_select(6, 60);
      1
 (1 row)
 
--- test that we don't crash on failing parameterized insert on the partition column
+-- Test that parameterized partition column for an insert is supported
 PREPARE prepared_partition_column_insert(bigint) AS
 INSERT INTO router_executor_table VALUES ($1, 'arsenous', '(1,10)');
--- we error out on the 6th execution
+-- execute 6 times to trigger prepared statement usage
 EXECUTE prepared_partition_column_insert(1);
 EXECUTE prepared_partition_column_insert(2);
 EXECUTE prepared_partition_column_insert(3);
 EXECUTE prepared_partition_column_insert(4);
 EXECUTE prepared_partition_column_insert(5);
 EXECUTE prepared_partition_column_insert(6);
-ERROR:  values given for the partition column must be constants or constant expressions
 DROP TYPE test_composite_type CASCADE;
 NOTICE:  drop cascades to table router_executor_table column stats
 -- test router executor with prepare statements
@@ -373,7 +376,6 @@ EXECUTE prepared_single_parameter_insert(3);
 EXECUTE prepared_single_parameter_insert(4);
 EXECUTE prepared_single_parameter_insert(5);
 EXECUTE prepared_single_parameter_insert(6);
-ERROR:  values given for the partition column must be constants or constant expressions
 PREPARE prepared_double_parameter_insert(int, int) AS
 	INSERT INTO prepare_table (key, value) VALUES ($1, $2);
 -- execute 6 times to trigger prepared statement usage
@@ -383,7 +385,6 @@ EXECUTE prepared_double_parameter_insert(3, 30);
 EXECUTE prepared_double_parameter_insert(4, 40);
 EXECUTE prepared_double_parameter_insert(5, 50);
 EXECUTE prepared_double_parameter_insert(6, 60);
-ERROR:  values given for the partition column must be constants or constant expressions
 PREPARE prepared_non_partition_parameter_insert(int) AS
 	INSERT INTO prepare_table (key, value) VALUES (0, $1);
 -- execute 6 times to trigger prepared statement usage
@@ -419,7 +420,9 @@ SELECT * FROM prepare_table ORDER BY key, value;
    4 |      
    5 |    50
    5 |      
-(22 rows)
+   6 |    60
+   6 |      
+(24 rows)
 
 -- check router executor select
 PREPARE prepared_router_partition_column_select(int) AS
@@ -468,9 +471,13 @@ EXECUTE prepared_router_partition_column_select(5);
    5 |      
 (2 rows)
 
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- EXECUTE prepared_router_partition_column_select(6);
+EXECUTE prepared_router_partition_column_select(6);
+ key | value 
+-----+-------
+   6 |    60
+   6 |      
+(2 rows)
+
 PREPARE prepared_router_non_partition_column_select(int) AS
 	SELECT
 		prepare_table.key,
@@ -566,9 +573,13 @@ EXECUTE prepared_real_time_non_partition_column_select(50);
    5 |    50
 (2 rows)
 
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- EXECUTE prepared_real_time_non_partition_column_select(60);
+EXECUTE prepared_real_time_non_partition_column_select(60);
+ key | value 
+-----+-------
+   0 |    60
+   6 |    60
+(2 rows)
+
 PREPARE prepared_real_time_partition_column_select(int) AS
 	SELECT
 		prepare_table.key,
@@ -625,9 +636,15 @@ EXECUTE prepared_real_time_partition_column_select(5);
    5 |      
 (4 rows)
 
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- EXECUTE prepared_real_time_partition_column_select(6);
+EXECUTE prepared_real_time_partition_column_select(6);
+ key | value 
+-----+-------
+   0 |    10
+   1 |    10
+   6 |    60
+   6 |      
+(4 rows)
+
 -- check task-tracker executor
 SET citus.task_executor_type TO 'task-tracker';
 PREPARE prepared_task_tracker_non_partition_column_select(int) AS
@@ -676,9 +693,13 @@ EXECUTE prepared_task_tracker_non_partition_column_select(50);
    5 |    50
 (2 rows)
 
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- EXECUTE prepared_task_tracker_non_partition_column_select(60);
+EXECUTE prepared_task_tracker_non_partition_column_select(60);
+ key | value 
+-----+-------
+   0 |    60
+   6 |    60
+(2 rows)
+
 PREPARE prepared_task_tracker_partition_column_select(int) AS
 	SELECT
 		prepare_table.key,
@@ -735,9 +756,15 @@ EXECUTE prepared_task_tracker_partition_column_select(5);
    5 |      
 (4 rows)
 
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- EXECUTE prepared_task_tracker_partition_column_select(6);
+EXECUTE prepared_task_tracker_partition_column_select(6);
+ key | value 
+-----+-------
+   0 |    10
+   1 |    10
+   6 |    60
+   6 |      
+(4 rows)
+
 SET citus.task_executor_type TO 'real-time';
 -- check updates
 PREPARE prepared_partition_parameter_update(int, int) AS
@@ -748,8 +775,7 @@ EXECUTE prepared_partition_parameter_update(2, 21);
 EXECUTE prepared_partition_parameter_update(3, 31);
 EXECUTE prepared_partition_parameter_update(4, 41);
 EXECUTE prepared_partition_parameter_update(5, 51);
--- This fails with an unexpected error message
-EXECUTE prepared_partition_parameter_update(5, 52);
+EXECUTE prepared_partition_parameter_update(6, 61);
 ERROR:  distributed modifications must target exactly one shard
 DETAIL:  This command modifies all shards.
 HINT:  Consider using an equality filter on partition column "key". You can use master_modify_multiple_shards() to perform multi-shard delete or update operations.
@@ -788,7 +814,9 @@ SELECT * FROM prepare_table ORDER BY key, value;
    4 |    41
    5 |    51
    5 |    51
-(22 rows)
+   6 |    60
+   6 |      
+(24 rows)
 
 -- check deletes
 PREPARE prepared_partition_parameter_delete(int, int) AS
@@ -798,8 +826,7 @@ EXECUTE prepared_partition_parameter_delete(2, 21);
 EXECUTE prepared_partition_parameter_delete(3, 31);
 EXECUTE prepared_partition_parameter_delete(4, 41);
 EXECUTE prepared_partition_parameter_delete(5, 51);
--- This fails with an unexpected error message
-EXECUTE prepared_partition_parameter_delete(0, 10);
+EXECUTE prepared_partition_parameter_delete(6, 61);
 ERROR:  distributed modifications must target exactly one shard
 DETAIL:  This command modifies all shards.
 HINT:  Consider using an equality filter on partition column "key". You can use master_modify_multiple_shards() to perform multi-shard delete or update operations.
@@ -822,7 +849,9 @@ SELECT * FROM prepare_table ORDER BY key, value;
    0 |      
    0 |      
    0 |      
-(6 rows)
+   6 |    60
+   6 |      
+(8 rows)
 
 -- verify placement state updates invalidate shard state
 --
diff --git a/src/test/regress/expected/multi_sql_function.out b/src/test/regress/expected/multi_sql_function.out
index e6882798d..5fea10339 100644
--- a/src/test/regress/expected/multi_sql_function.out
+++ b/src/test/regress/expected/multi_sql_function.out
@@ -315,7 +315,9 @@ SELECT * FROM prepare_table ORDER BY key, value;
    0 |      
    0 |      
    0 |      
-(6 rows)
+   6 |    60
+   6 |      
+(8 rows)
 
 DROP TABLE temp_table;
 -- clean-up functions
diff --git a/src/test/regress/sql/multi_explain.sql b/src/test/regress/sql/multi_explain.sql
index 9c445596c..c7874a38a 100644
--- a/src/test/regress/sql/multi_explain.sql
+++ b/src/test/regress/sql/multi_explain.sql
@@ -227,3 +227,8 @@ EXPLAIN EXECUTE router_executor_query;
 PREPARE real_time_executor_query AS
 	SELECT avg(l_linenumber) FROM lineitem WHERE l_orderkey > 9030;
 EXPLAIN (COSTS FALSE) EXECUTE real_time_executor_query;
+
+-- EXPLAIN EXECUTE of parametrized prepared statements is broken, but
+-- at least make sure to fail without crashing
+PREPARE router_executor_query_param(int) AS SELECT l_quantity FROM lineitem WHERE l_orderkey = $1;
+EXPLAIN EXECUTE router_executor_query_param(5);
diff --git a/src/test/regress/sql/multi_prepare_plsql.sql b/src/test/regress/sql/multi_prepare_plsql.sql
index cb1bab581..5018c2cb8 100644
--- a/src/test/regress/sql/multi_prepare_plsql.sql
+++ b/src/test/regress/sql/multi_prepare_plsql.sql
@@ -183,9 +183,8 @@ SELECT plpgsql_test_1();
 SELECT plpgsql_test_2();
 
 -- run PL/pgsql functions with different parameters
--- FIXME: temporarily disabled, waiting for proper parametrized query support
--- SELECT plpgsql_test_6(155);
--- SELECT plpgsql_test_6(1555);
+SELECT plpgsql_test_6(155);
+SELECT plpgsql_test_6(1555);
 
 -- test router executor parameterized PL/pgsql functions
 CREATE TABLE plpgsql_table (
@@ -276,15 +275,13 @@ BEGIN
 END;
 $$ LANGUAGE plpgsql;
 
+-- execute 6 times to trigger prepared statement usage
 SELECT router_partition_column_select(1);
 SELECT router_partition_column_select(2);
 SELECT router_partition_column_select(3);
 SELECT router_partition_column_select(4);
 SELECT router_partition_column_select(5);
-
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- SELECT router_partition_column_select(6);
+SELECT router_partition_column_select(6);
 
 CREATE FUNCTION router_non_partition_column_select(value_arg int)
 	RETURNS TABLE(key int, value int) AS $$
@@ -305,6 +302,7 @@ BEGIN
 END;
 $$ LANGUAGE plpgsql;
 
+-- execute 6 times to trigger prepared statement usage
 SELECT router_non_partition_column_select(10);
 SELECT router_non_partition_column_select(20);
 SELECT router_non_partition_column_select(30);
@@ -331,15 +329,13 @@ BEGIN
 END;
 $$ LANGUAGE plpgsql;
 
+-- execute 6 times to trigger prepared statement usage
 SELECT real_time_non_partition_column_select(10);
 SELECT real_time_non_partition_column_select(20);
 SELECT real_time_non_partition_column_select(30);
 SELECT real_time_non_partition_column_select(40);
 SELECT real_time_non_partition_column_select(50);
-
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- SELECT real_time_non_partition_column_select(60);
+SELECT real_time_non_partition_column_select(60);
 
 CREATE FUNCTION real_time_partition_column_select(key_arg int)
 	RETURNS TABLE(key int, value int) AS $$
@@ -360,15 +356,13 @@ BEGIN
 END;
 $$ LANGUAGE plpgsql;
 
+-- execute 6 times to trigger prepared statement usage
 SELECT real_time_partition_column_select(1);
 SELECT real_time_partition_column_select(2);
 SELECT real_time_partition_column_select(3);
 SELECT real_time_partition_column_select(4);
 SELECT real_time_partition_column_select(5);
-
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- SELECT real_time_partition_column_select(6);
+SELECT real_time_partition_column_select(6);
 
 -- check task-tracker executor
 SET citus.task_executor_type TO 'task-tracker';
@@ -391,15 +385,13 @@ BEGIN
 END;
 $$ LANGUAGE plpgsql;
 
+-- execute 6 times to trigger prepared statement usage
 SELECT task_tracker_non_partition_column_select(10);
 SELECT task_tracker_non_partition_column_select(20);
 SELECT task_tracker_non_partition_column_select(30);
 SELECT task_tracker_non_partition_column_select(40);
 SELECT task_tracker_non_partition_column_select(50);
-
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- SELECT real_time_non_partition_column_select(60);
+SELECT real_time_non_partition_column_select(60);
 
 CREATE FUNCTION task_tracker_partition_column_select(key_arg int)
 	RETURNS TABLE(key int, value int) AS $$
@@ -420,15 +412,13 @@ BEGIN
 END;
 $$ LANGUAGE plpgsql;
 
+-- execute 6 times to trigger prepared statement usage
 SELECT task_tracker_partition_column_select(1);
 SELECT task_tracker_partition_column_select(2);
 SELECT task_tracker_partition_column_select(3);
 SELECT task_tracker_partition_column_select(4);
 SELECT task_tracker_partition_column_select(5);
-
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- SELECT task_tracker_partition_column_select(6);
+SELECT task_tracker_partition_column_select(6);
 
 SET citus.task_executor_type TO 'real-time';
 
@@ -445,8 +435,7 @@ SELECT partition_parameter_update(2, 21);
 SELECT partition_parameter_update(3, 31);
 SELECT partition_parameter_update(4, 41);
 SELECT partition_parameter_update(5, 51);
--- This fails with an unexpected error message
-SELECT partition_parameter_update(5, 52);
+SELECT partition_parameter_update(6, 61);
 
 CREATE FUNCTION non_partition_parameter_update(int, int) RETURNS void as $$
 BEGIN
@@ -472,13 +461,13 @@ BEGIN
 END;
 $$ LANGUAGE plpgsql;
 
+-- execute 6 times to trigger prepared statement usage
 SELECT partition_parameter_delete(1, 11);
 SELECT partition_parameter_delete(2, 21);
 SELECT partition_parameter_delete(3, 31);
 SELECT partition_parameter_delete(4, 41);
 SELECT partition_parameter_delete(5, 51);
--- This fails with an unexpected error message
-SELECT partition_parameter_delete(0, 10);
+SELECT partition_parameter_delete(6, 61);
 
 CREATE FUNCTION  non_partition_parameter_delete(int) RETURNS void as $$
 BEGIN
diff --git a/src/test/regress/sql/multi_prepare_sql.sql b/src/test/regress/sql/multi_prepare_sql.sql
index 8618b8f76..d35c5d936 100644
--- a/src/test/regress/sql/multi_prepare_sql.sql
+++ b/src/test/regress/sql/multi_prepare_sql.sql
@@ -149,8 +149,7 @@ EXECUTE prepared_test_2;
 
 -- execute prepared statements with different parameters
 EXECUTE prepared_test_6(155);
--- FIXME: temporarily disabled
--- EXECUTE prepared_test_6(1555);
+EXECUTE prepared_test_6(1555);
 
 -- test router executor with parameterized non-partition columns
 
@@ -194,12 +193,12 @@ EXECUTE prepared_select(4, 40);
 EXECUTE prepared_select(5, 50);
 EXECUTE prepared_select(6, 60);
 
--- test that we don't crash on failing parameterized insert on the partition column
+-- Test that parameterized partition column for an insert is supported
 
 PREPARE prepared_partition_column_insert(bigint) AS
 INSERT INTO router_executor_table VALUES ($1, 'arsenous', '(1,10)');
 
--- we error out on the 6th execution
+-- execute 6 times to trigger prepared statement usage
 EXECUTE prepared_partition_column_insert(1);
 EXECUTE prepared_partition_column_insert(2);
 EXECUTE prepared_partition_column_insert(3);
@@ -282,10 +281,7 @@ EXECUTE prepared_router_partition_column_select(2);
 EXECUTE prepared_router_partition_column_select(3);
 EXECUTE prepared_router_partition_column_select(4);
 EXECUTE prepared_router_partition_column_select(5);
-
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- EXECUTE prepared_router_partition_column_select(6);
+EXECUTE prepared_router_partition_column_select(6);
 
 PREPARE prepared_router_non_partition_column_select(int) AS
 	SELECT
@@ -325,10 +321,7 @@ EXECUTE prepared_real_time_non_partition_column_select(20);
 EXECUTE prepared_real_time_non_partition_column_select(30);
 EXECUTE prepared_real_time_non_partition_column_select(40);
 EXECUTE prepared_real_time_non_partition_column_select(50);
-
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- EXECUTE prepared_real_time_non_partition_column_select(60);
+EXECUTE prepared_real_time_non_partition_column_select(60);
 
 PREPARE prepared_real_time_partition_column_select(int) AS
 	SELECT
@@ -348,10 +341,7 @@ EXECUTE prepared_real_time_partition_column_select(2);
 EXECUTE prepared_real_time_partition_column_select(3);
 EXECUTE prepared_real_time_partition_column_select(4);
 EXECUTE prepared_real_time_partition_column_select(5);
-
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- EXECUTE prepared_real_time_partition_column_select(6);
+EXECUTE prepared_real_time_partition_column_select(6);
 
 -- check task-tracker executor
 SET citus.task_executor_type TO 'task-tracker';
@@ -373,10 +363,7 @@ EXECUTE prepared_task_tracker_non_partition_column_select(20);
 EXECUTE prepared_task_tracker_non_partition_column_select(30);
 EXECUTE prepared_task_tracker_non_partition_column_select(40);
 EXECUTE prepared_task_tracker_non_partition_column_select(50);
-
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- EXECUTE prepared_task_tracker_non_partition_column_select(60);
+EXECUTE prepared_task_tracker_non_partition_column_select(60);
 
 PREPARE prepared_task_tracker_partition_column_select(int) AS
 	SELECT
@@ -396,10 +383,7 @@ EXECUTE prepared_task_tracker_partition_column_select(2);
 EXECUTE prepared_task_tracker_partition_column_select(3);
 EXECUTE prepared_task_tracker_partition_column_select(4);
 EXECUTE prepared_task_tracker_partition_column_select(5);
-
--- FIXME: 6th execution is failing. We don't want to run the failing test
--- because of changing output. After implementing this feature, uncomment this.
--- EXECUTE prepared_task_tracker_partition_column_select(6);
+EXECUTE prepared_task_tracker_partition_column_select(6);
 
 SET citus.task_executor_type TO 'real-time';
 
@@ -413,8 +397,7 @@ EXECUTE prepared_partition_parameter_update(2, 21);
 EXECUTE prepared_partition_parameter_update(3, 31);
 EXECUTE prepared_partition_parameter_update(4, 41);
 EXECUTE prepared_partition_parameter_update(5, 51);
--- This fails with an unexpected error message
-EXECUTE prepared_partition_parameter_update(5, 52);
+EXECUTE prepared_partition_parameter_update(6, 61);
 
 PREPARE prepared_non_partition_parameter_update(int, int) AS
 	UPDATE prepare_table SET value = $2 WHERE key = 0 AND value = $1;
@@ -439,8 +422,7 @@ EXECUTE prepared_partition_parameter_delete(2, 21);
 EXECUTE prepared_partition_parameter_delete(3, 31);
 EXECUTE prepared_partition_parameter_delete(4, 41);
 EXECUTE prepared_partition_parameter_delete(5, 51);
--- This fails with an unexpected error message
-EXECUTE prepared_partition_parameter_delete(0, 10);
+EXECUTE prepared_partition_parameter_delete(6, 61);
 
 PREPARE prepared_non_partition_parameter_delete(int) AS
 	DELETE FROM prepare_table WHERE key = 0 AND value = $1;