diff --git a/.github/workflows/build_and_test.yml b/.github/workflows/build_and_test.yml
index cf63effc07b..305c11aa66f 100644
--- a/.github/workflows/build_and_test.yml
+++ b/.github/workflows/build_and_test.yml
@@ -36,11 +36,11 @@ jobs:
       style_checker_image_name: "ghcr.io/citusdata/stylechecker"
       style_checker_tools_version: "0.8.33"
       sql_snapshot_pg_version: "18.6"
-      image_suffix: "-vb652ec7"
+      image_suffix: "-va0a5582"
       pg17_version: '{ "major": "17", "full": "17.11" }'
       pg18_version: '{ "major": "18", "full": "18.6" }'
-      pg19_version: '{ "major": "19", "full": "19beta4" }'
-      upgrade_pg_versions: "17.11-18.6-19beta4"
+      pg19_version: '{ "major": "19", "full": "19rc1" }'
+      upgrade_pg_versions: "17.11-18.6-19rc1"
     steps:
       # Since GHA jobs need at least one step we use a noop step here.
       - name: Set up parameters
diff --git a/.github/workflows/nightly_cassert.yml b/.github/workflows/nightly_cassert.yml
index 5e5bf8329ed..bbf69cd82e7 100644
--- a/.github/workflows/nightly_cassert.yml
+++ b/.github/workflows/nightly_cassert.yml
@@ -7,7 +7,7 @@ run-name: Nightly cassert (${{ github.ref_name }})
 # asserts surface -- that is the intended signal, not a regression gate.
 #
 # The version matrix lives in the `params` job below (single source of truth, mirroring
-# build_and_test.yml's params job, which pins 17.11 / 18.6 / 19beta4 and no longer builds PG16).
+# build_and_test.yml's params job, which pins 17.11 / 18.6 / 19rc1 and no longer builds PG16).
 
 on:
   schedule:
@@ -34,8 +34,8 @@ jobs:
     name: Initialize parameters
     runs-on: ubuntu-latest
     outputs:
-      pg_versions: '[{ "major": "17", "full": "17.11" }, { "major": "18", "full": "18.6" }, { "major": "19", "full": "19beta4" }]'
-      pg_upgrade_pairs: '[{ "old": "17", "old_full": "17.11", "new": "18", "new_full": "18.6" }, { "old": "18", "old_full": "18.6", "new": "19", "new_full": "19beta4" }, { "old": "17", "old_full": "17.11", "new": "19", "new_full": "19beta4" }]'
+      pg_versions: '[{ "major": "17", "full": "17.11" }, { "major": "18", "full": "18.6" }, { "major": "19", "full": "19rc1" }]'
+      pg_upgrade_pairs: '[{ "old": "17", "old_full": "17.11", "new": "18", "new_full": "18.6" }, { "old": "18", "old_full": "18.6", "new": "19", "new_full": "19rc1" }, { "old": "17", "old_full": "17.11", "new": "19", "new_full": "19rc1" }]'
       citus_upgrade_pg: '[{ "major": "17", "full": "17.11" }, { "major": "18", "full": "18.6" }]'
       citus_old_version: "v14.0.1"  # 14.0-1 chains to MASTER (15.0); 14.1 has no path to 15.0 yet
     steps:
diff --git a/src/test/regress/expected/pg19.out b/src/test/regress/expected/pg19.out
index c0332de3438..6ca3c1f48df 100644
--- a/src/test/regress/expected/pg19.out
+++ b/src/test/regress/expected/pg19.out
@@ -810,6 +810,30 @@ COPY json_copy_dist TO STDOUT (FORMAT json, HEADER true);
 ERROR:  cannot specify HEADER in JSON mode
 DROP TABLE json_copy_dist, json_copy_empty, json_copy_single_shard,
            json_copy_reference, json_copy_local, json_copy_citus_local;
+-- PG19 RC1 fixed ON CONFLICT inference when an index expression on a NOT NULL
+-- column simplifies to that column. Keep the distribution key as a plain index
+-- key too, so the unique index is enforceable across shards.
+-- PG19 commit: https://github.com/postgres/postgres/commit/f9ccc5e4f92bc39f7c31905ff611785ff29ab9bb
+CREATE TABLE on_conflict_nn_expr (a int NOT NULL, b text NOT NULL, payload int);
+SELECT create_distributed_table('on_conflict_nn_expr', 'a');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+CREATE UNIQUE INDEX on_conflict_nn_expr_idx
+    ON on_conflict_nn_expr (COALESCE(a, 0), lower(b), a);
+INSERT INTO on_conflict_nn_expr VALUES (1, 'Alice', 10);
+INSERT INTO on_conflict_nn_expr VALUES (1, 'ALICE', 20)
+    ON CONFLICT (a int4_ops, lower(b))
+    DO UPDATE SET payload = EXCLUDED.payload;
+SELECT a, b, payload FROM on_conflict_nn_expr;
+ a |   b   | payload
+---------------------------------------------------------------------
+ 1 | Alice |      20
+(1 row)
+
+DROP TABLE on_conflict_nn_expr;
 SELECT citus_remove_node('localhost', :master_port);
  citus_remove_node
 ---------------------------------------------------------------------
diff --git a/src/test/regress/sql/pg19.sql b/src/test/regress/sql/pg19.sql
index 947da2e885c..f071e349358 100644
--- a/src/test/regress/sql/pg19.sql
+++ b/src/test/regress/sql/pg19.sql
@@ -593,6 +593,24 @@ COPY json_copy_dist TO STDOUT (FORMAT json, HEADER true);
 DROP TABLE json_copy_dist, json_copy_empty, json_copy_single_shard,
            json_copy_reference, json_copy_local, json_copy_citus_local;
 
+-- PG19 RC1 fixed ON CONFLICT inference when an index expression on a NOT NULL
+-- column simplifies to that column. Keep the distribution key as a plain index
+-- key too, so the unique index is enforceable across shards.
+-- PG19 commit: https://github.com/postgres/postgres/commit/f9ccc5e4f92bc39f7c31905ff611785ff29ab9bb
+CREATE TABLE on_conflict_nn_expr (a int NOT NULL, b text NOT NULL, payload int);
+SELECT create_distributed_table('on_conflict_nn_expr', 'a');
+CREATE UNIQUE INDEX on_conflict_nn_expr_idx
+    ON on_conflict_nn_expr (COALESCE(a, 0), lower(b), a);
+
+INSERT INTO on_conflict_nn_expr VALUES (1, 'Alice', 10);
+INSERT INTO on_conflict_nn_expr VALUES (1, 'ALICE', 20)
+    ON CONFLICT (a int4_ops, lower(b))
+    DO UPDATE SET payload = EXCLUDED.payload;
+
+SELECT a, b, payload FROM on_conflict_nn_expr;
+
+DROP TABLE on_conflict_nn_expr;
+
 SELECT citus_remove_node('localhost', :master_port);
 RESET client_min_messages;