diff --git a/.devcontainer/Dockerfile b/.devcontainer/Dockerfile
index 6579c52d9..4819209a3 100644
--- a/.devcontainer/Dockerfile
+++ b/.devcontainer/Dockerfile
@@ -72,18 +72,6 @@ ENV PATH="/home/citus/.pgenv/pgsql/bin:${PATH}"
 USER citus
 
 # build postgres versions separately for effective parrallelism and caching of already built versions when changing only certain versions
-FROM base AS pg15
-RUN MAKEFLAGS="-j $(nproc)" pgenv build 15.14
-RUN rm .pgenv/src/*.tar*
-RUN make -C .pgenv/src/postgresql-*/ clean
-RUN make -C .pgenv/src/postgresql-*/src/include install
-
-# create a staging directory with all files we want to copy from our pgenv build
-# we will copy the contents of the staged folder into the final image at once
-RUN mkdir .pgenv-staging/
-RUN cp -r .pgenv/src .pgenv/pgsql-* .pgenv/config .pgenv-staging/
-RUN rm .pgenv-staging/config/default.conf
-
 FROM base AS pg16
 RUN MAKEFLAGS="-j $(nproc)" pgenv build 16.10
 RUN rm .pgenv/src/*.tar*
@@ -198,7 +186,6 @@ RUN git clone https://github.com/so-fancy/diff-so-fancy.git \
 
 COPY --link --from=uncrustify-builder /uncrustify/usr/ /usr/
 
-COPY --link --from=pg15 /home/citus/.pgenv-staging/ /home/citus/.pgenv/
 COPY --link --from=pg16 /home/citus/.pgenv-staging/ /home/citus/.pgenv/
 COPY --link --from=pg17 /home/citus/.pgenv-staging/ /home/citus/.pgenv/
 
diff --git a/.github/workflows/build_and_test.yml b/.github/workflows/build_and_test.yml
index 98e012179..d0be0ce0d 100644
--- a/.github/workflows/build_and_test.yml
+++ b/.github/workflows/build_and_test.yml
@@ -32,11 +32,10 @@ jobs:
       style_checker_image_name: "ghcr.io/citusdata/stylechecker"
       style_checker_tools_version: "0.8.18"
       sql_snapshot_pg_version: "17.6"
-      image_suffix: "-va20872f"
-      pg15_version: '{ "major": "15", "full": "15.14" }'
+      image_suffix: "-dev-76e863d"
       pg16_version: '{ "major": "16", "full": "16.10" }'
       pg17_version: '{ "major": "17", "full": "17.6" }'
-      upgrade_pg_versions: "15.14-16.10-17.6"
+      upgrade_pg_versions: "16.10-17.6"
     steps:
       # Since GHA jobs need at least one step we use a noop step here.
       - name: Set up parameters
@@ -110,7 +109,6 @@ jobs:
         image_suffix:
           - ${{ needs.params.outputs.image_suffix}}
         pg_version:
-          - ${{ needs.params.outputs.pg15_version }}
           - ${{ needs.params.outputs.pg16_version }}
           - ${{ needs.params.outputs.pg17_version }}
     runs-on: ubuntu-latest
@@ -141,7 +139,6 @@ jobs:
         image_name:
           - ${{ needs.params.outputs.test_image_name }}
         pg_version:
-          - ${{ needs.params.outputs.pg15_version }}
           - ${{ needs.params.outputs.pg16_version }}
           - ${{ needs.params.outputs.pg17_version }}
         make:
@@ -162,10 +159,6 @@ jobs:
           - check-enterprise-isolation-logicalrep-2
           - check-enterprise-isolation-logicalrep-3
         include:
-          - make: check-failure
-            pg_version: ${{ needs.params.outputs.pg15_version }}
-            suite: regress
-            image_name: ${{ needs.params.outputs.fail_test_image_name }}
           - make: check-failure
             pg_version: ${{ needs.params.outputs.pg16_version }}
             suite: regress
@@ -174,10 +167,6 @@ jobs:
             pg_version: ${{ needs.params.outputs.pg17_version }}
             suite: regress
             image_name: ${{ needs.params.outputs.fail_test_image_name }}
-          - make: check-enterprise-failure
-            pg_version: ${{ needs.params.outputs.pg15_version }}
-            suite: regress
-            image_name: ${{ needs.params.outputs.fail_test_image_name }}
           - make: check-enterprise-failure
             pg_version: ${{ needs.params.outputs.pg16_version }}
             suite: regress
@@ -186,10 +175,6 @@ jobs:
             pg_version: ${{ needs.params.outputs.pg17_version }}
             suite: regress
             image_name: ${{ needs.params.outputs.fail_test_image_name }}
-          - make: check-pytest
-            pg_version: ${{ needs.params.outputs.pg15_version }}
-            suite: regress
-            image_name: ${{ needs.params.outputs.fail_test_image_name }}
           - make: check-pytest
             pg_version: ${{ needs.params.outputs.pg16_version }}
             suite: regress
@@ -198,10 +183,6 @@ jobs:
             pg_version: ${{ needs.params.outputs.pg17_version }}
             suite: regress
             image_name: ${{ needs.params.outputs.fail_test_image_name }}
-          - make: installcheck
-            suite: cdc
-            image_name: ${{ needs.params.outputs.test_image_name }}
-            pg_version: ${{ needs.params.outputs.pg15_version }}
           - make: installcheck
             suite: cdc
             image_name: ${{ needs.params.outputs.test_image_name }}
@@ -210,10 +191,6 @@ jobs:
             suite: cdc
             image_name: ${{ needs.params.outputs.test_image_name }}
             pg_version: ${{ needs.params.outputs.pg17_version }}
-          - make: check-query-generator
-            pg_version: ${{ needs.params.outputs.pg15_version }}
-            suite: regress
-            image_name: ${{ needs.params.outputs.fail_test_image_name }}
           - make: check-query-generator
             pg_version: ${{ needs.params.outputs.pg16_version }}
             suite: regress
@@ -268,7 +245,6 @@ jobs:
         image_name:
           - ${{ needs.params.outputs.fail_test_image_name }}
         pg_version:
-          - ${{ needs.params.outputs.pg15_version }}
           - ${{ needs.params.outputs.pg16_version }}
           - ${{ needs.params.outputs.pg17_version }}
         parallel: [0,1,2,3,4,5] # workaround for running 6 parallel jobs
@@ -315,12 +291,8 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - old_pg_major: 15
-            new_pg_major: 16
           - old_pg_major: 16
             new_pg_major: 17
-          - old_pg_major: 15
-            new_pg_major: 17
     env:
       old_pg_major: ${{ matrix.old_pg_major }}
       new_pg_major: ${{ matrix.new_pg_major }}
@@ -376,7 +348,6 @@ jobs:
       fail-fast: false
       matrix:
         pg_version:
-          - ${{ needs.params.outputs.pg15_version }}
           - ${{ needs.params.outputs.pg16_version }}
     steps:
     - uses: actions/checkout@v4
diff --git a/.github/workflows/flaky_test_debugging.yml b/.github/workflows/flaky_test_debugging.yml
index 055ba6c6a..e7e56215d 100644
--- a/.github/workflows/flaky_test_debugging.yml
+++ b/.github/workflows/flaky_test_debugging.yml
@@ -25,7 +25,7 @@ jobs:
     name: Build Citus
     runs-on: ubuntu-latest
     container:
-      image: ${{ vars.build_image_name }}:${{ vars.pg15_version  }}${{ vars.image_suffix }}
+      image: ${{ vars.build_image_name }}:${{ vars.pg16_version  }}${{ vars.image_suffix }}
       options: --user root
     steps:
     - uses: actions/checkout@v4
@@ -55,7 +55,7 @@ jobs:
     name: Test flakyness
     runs-on: ubuntu-latest
     container:
-      image: ${{ vars.fail_test_image_name }}:${{ vars.pg15_version  }}${{ vars.image_suffix }}
+      image: ${{ vars.fail_test_image_name }}:${{ vars.pg16_version  }}${{ vars.image_suffix }}
       options: --user root
     needs:
       [build, prepare_parallelization_matrix]