diff --git a/CHANGELOG.md b/CHANGELOG.md
index ff4e2d3bf..7bca7fa9d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@ See the [releases page](https://github.com/github/codeql-action/releases) for th
 ## [UNRELEASED]
 
 - Fixed a bug where two diagnostics produced within the same millisecond could overwrite each other on disk, causing one of them to be lost. [#3852](https://github.com/github/codeql-action/pull/3852)
+- _Upcoming breaking change_: Add a deprecation warning for customers using CodeQL version 2.19.3 and earlier. These versions of CodeQL were discontinued on 9 April 2026 alongside GitHub Enterprise Server 3.15, and will be unsupported by the next minor release of the CodeQL Action. [#3837](https://github.com/github/codeql-action/pull/3837)
 
 ## 4.35.2 - 15 Apr 2026
 
diff --git a/lib/analyze-action-post.js b/lib/analyze-action-post.js
index 78954afbe..e09612b2c 100644
--- a/lib/analyze-action-post.js
+++ b/lib/analyze-action-post.js
@@ -163010,9 +163010,9 @@ async function shouldEnableIndirectTracing(codeql, config) {
 // src/codeql.ts
 var cachedCodeQL = void 0;
 var CODEQL_MINIMUM_VERSION = "2.17.6";
-var CODEQL_NEXT_MINIMUM_VERSION = "2.17.6";
-var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.13";
-var GHES_MOST_RECENT_DEPRECATION_DATE = "2025-06-19";
+var CODEQL_NEXT_MINIMUM_VERSION = "2.19.4";
+var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.15";
+var GHES_MOST_RECENT_DEPRECATION_DATE = "2026-04-09";
 var EXTRACTION_DEBUG_MODE_VERBOSITY = "progress++";
 async function getCodeQL(cmd) {
   if (cachedCodeQL === void 0) {
diff --git a/lib/analyze-action.js b/lib/analyze-action.js
index 750a0e52d..372021fc2 100644
--- a/lib/analyze-action.js
+++ b/lib/analyze-action.js
@@ -110045,9 +110045,9 @@ async function endTracingForCluster(codeql, config, logger) {
 // src/codeql.ts
 var cachedCodeQL = void 0;
 var CODEQL_MINIMUM_VERSION = "2.17.6";
-var CODEQL_NEXT_MINIMUM_VERSION = "2.17.6";
-var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.13";
-var GHES_MOST_RECENT_DEPRECATION_DATE = "2025-06-19";
+var CODEQL_NEXT_MINIMUM_VERSION = "2.19.4";
+var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.15";
+var GHES_MOST_RECENT_DEPRECATION_DATE = "2026-04-09";
 var EXTRACTION_DEBUG_MODE_VERBOSITY = "progress++";
 async function setupCodeQL(toolsInput, apiDetails, tempDir, variant, defaultCliVersion, features, logger, checkVersion) {
   try {
diff --git a/lib/autobuild-action.js b/lib/autobuild-action.js
index 379911bd5..6825745a3 100644
--- a/lib/autobuild-action.js
+++ b/lib/autobuild-action.js
@@ -105422,9 +105422,9 @@ async function endTracingForCluster(codeql, config, logger) {
 // src/codeql.ts
 var cachedCodeQL = void 0;
 var CODEQL_MINIMUM_VERSION = "2.17.6";
-var CODEQL_NEXT_MINIMUM_VERSION = "2.17.6";
-var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.13";
-var GHES_MOST_RECENT_DEPRECATION_DATE = "2025-06-19";
+var CODEQL_NEXT_MINIMUM_VERSION = "2.19.4";
+var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.15";
+var GHES_MOST_RECENT_DEPRECATION_DATE = "2026-04-09";
 var EXTRACTION_DEBUG_MODE_VERBOSITY = "progress++";
 async function getCodeQL(cmd) {
   if (cachedCodeQL === void 0) {
diff --git a/lib/init-action-post.js b/lib/init-action-post.js
index 2e065ac6b..e8dc72e0b 100644
--- a/lib/init-action-post.js
+++ b/lib/init-action-post.js
@@ -167857,9 +167857,9 @@ async function shouldEnableIndirectTracing(codeql, config) {
 // src/codeql.ts
 var cachedCodeQL = void 0;
 var CODEQL_MINIMUM_VERSION = "2.17.6";
-var CODEQL_NEXT_MINIMUM_VERSION = "2.17.6";
-var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.13";
-var GHES_MOST_RECENT_DEPRECATION_DATE = "2025-06-19";
+var CODEQL_NEXT_MINIMUM_VERSION = "2.19.4";
+var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.15";
+var GHES_MOST_RECENT_DEPRECATION_DATE = "2026-04-09";
 var EXTRACTION_DEBUG_MODE_VERBOSITY = "progress++";
 async function setupCodeQL(toolsInput, apiDetails, tempDir, variant, defaultCliVersion, features, logger, checkVersion) {
   try {
diff --git a/lib/init-action.js b/lib/init-action.js
index 1970c1279..d0b0a8b61 100644
--- a/lib/init-action.js
+++ b/lib/init-action.js
@@ -108975,9 +108975,9 @@ async function getCombinedTracerConfig(codeql, config) {
 // src/codeql.ts
 var cachedCodeQL = void 0;
 var CODEQL_MINIMUM_VERSION = "2.17.6";
-var CODEQL_NEXT_MINIMUM_VERSION = "2.17.6";
-var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.13";
-var GHES_MOST_RECENT_DEPRECATION_DATE = "2025-06-19";
+var CODEQL_NEXT_MINIMUM_VERSION = "2.19.4";
+var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.15";
+var GHES_MOST_RECENT_DEPRECATION_DATE = "2026-04-09";
 var EXTRACTION_DEBUG_MODE_VERBOSITY = "progress++";
 async function setupCodeQL(toolsInput, apiDetails, tempDir, variant, defaultCliVersion, features, logger, checkVersion) {
   try {
diff --git a/lib/resolve-environment-action.js b/lib/resolve-environment-action.js
index 5fa8073dd..87def4ccd 100644
--- a/lib/resolve-environment-action.js
+++ b/lib/resolve-environment-action.js
@@ -105059,9 +105059,9 @@ async function shouldEnableIndirectTracing(codeql, config) {
 // src/codeql.ts
 var cachedCodeQL = void 0;
 var CODEQL_MINIMUM_VERSION = "2.17.6";
-var CODEQL_NEXT_MINIMUM_VERSION = "2.17.6";
-var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.13";
-var GHES_MOST_RECENT_DEPRECATION_DATE = "2025-06-19";
+var CODEQL_NEXT_MINIMUM_VERSION = "2.19.4";
+var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.15";
+var GHES_MOST_RECENT_DEPRECATION_DATE = "2026-04-09";
 var EXTRACTION_DEBUG_MODE_VERBOSITY = "progress++";
 async function getCodeQL(cmd) {
   if (cachedCodeQL === void 0) {
diff --git a/lib/setup-codeql-action.js b/lib/setup-codeql-action.js
index 636a142b8..a2699cb27 100644
--- a/lib/setup-codeql-action.js
+++ b/lib/setup-codeql-action.js
@@ -106468,9 +106468,9 @@ async function shouldEnableIndirectTracing(codeql, config) {
 // src/codeql.ts
 var cachedCodeQL = void 0;
 var CODEQL_MINIMUM_VERSION = "2.17.6";
-var CODEQL_NEXT_MINIMUM_VERSION = "2.17.6";
-var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.13";
-var GHES_MOST_RECENT_DEPRECATION_DATE = "2025-06-19";
+var CODEQL_NEXT_MINIMUM_VERSION = "2.19.4";
+var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.15";
+var GHES_MOST_RECENT_DEPRECATION_DATE = "2026-04-09";
 var EXTRACTION_DEBUG_MODE_VERBOSITY = "progress++";
 async function setupCodeQL(toolsInput, apiDetails, tempDir, variant, defaultCliVersion, features, logger, checkVersion) {
   try {
diff --git a/lib/upload-lib.js b/lib/upload-lib.js
index 4bd41931b..0d9ffc35e 100644
--- a/lib/upload-lib.js
+++ b/lib/upload-lib.js
@@ -109154,9 +109154,9 @@ async function shouldEnableIndirectTracing(codeql, config) {
 // src/codeql.ts
 var cachedCodeQL = void 0;
 var CODEQL_MINIMUM_VERSION = "2.17.6";
-var CODEQL_NEXT_MINIMUM_VERSION = "2.17.6";
-var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.13";
-var GHES_MOST_RECENT_DEPRECATION_DATE = "2025-06-19";
+var CODEQL_NEXT_MINIMUM_VERSION = "2.19.4";
+var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.15";
+var GHES_MOST_RECENT_DEPRECATION_DATE = "2026-04-09";
 var EXTRACTION_DEBUG_MODE_VERBOSITY = "progress++";
 async function setupCodeQL(toolsInput, apiDetails, tempDir, variant, defaultCliVersion, features, logger, checkVersion) {
   try {
diff --git a/lib/upload-sarif-action.js b/lib/upload-sarif-action.js
index e6ca76b23..02f6c1fb3 100644
--- a/lib/upload-sarif-action.js
+++ b/lib/upload-sarif-action.js
@@ -109820,9 +109820,9 @@ async function shouldEnableIndirectTracing(codeql, config) {
 // src/codeql.ts
 var cachedCodeQL = void 0;
 var CODEQL_MINIMUM_VERSION = "2.17.6";
-var CODEQL_NEXT_MINIMUM_VERSION = "2.17.6";
-var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.13";
-var GHES_MOST_RECENT_DEPRECATION_DATE = "2025-06-19";
+var CODEQL_NEXT_MINIMUM_VERSION = "2.19.4";
+var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.15";
+var GHES_MOST_RECENT_DEPRECATION_DATE = "2026-04-09";
 var EXTRACTION_DEBUG_MODE_VERBOSITY = "progress++";
 async function setupCodeQL(toolsInput, apiDetails, tempDir, variant, defaultCliVersion, features, logger, checkVersion) {
   try {
diff --git a/src/codeql.ts b/src/codeql.ts
index fda355033..ecad2ea19 100644
--- a/src/codeql.ts
+++ b/src/codeql.ts
@@ -282,17 +282,17 @@ const CODEQL_MINIMUM_VERSION = "2.17.6";
 /**
  * This version will shortly become the oldest version of CodeQL that the Action will run with.
  */
-const CODEQL_NEXT_MINIMUM_VERSION = "2.17.6";
+const CODEQL_NEXT_MINIMUM_VERSION = "2.19.4";
 
 /**
  * This is the version of GHES that was most recently deprecated.
  */
-const GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.13";
+const GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.15";
 
 /**
  * This is the deprecation date for the version of GHES that was most recently deprecated.
  */
-const GHES_MOST_RECENT_DEPRECATION_DATE = "2025-06-19";
+const GHES_MOST_RECENT_DEPRECATION_DATE = "2026-04-09";
 
 /** The CLI verbosity level to use for extraction in debug mode. */
 const EXTRACTION_DEBUG_MODE_VERBOSITY = "progress++";