diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1c0d6f84ea..fa77094416 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,7 +4,7 @@ See the [releases page](https://github.com/github/codeql-action/releases) for th
 
 ## [UNRELEASED]
 
-No user facing changes.
+- _Upcoming breaking change_: Add a deprecation warning for customers using CodeQL version 2.20.6 and earlier. These versions of CodeQL were discontinued on 1 July 2026 alongside GitHub Enterprise Server 3.16, and will be unsupported by the next minor release of the CodeQL Action. [#3956](https://github.com/github/codeql-action/pull/3956)
 
 ## 4.36.2 - 04 Jun 2026
 
diff --git a/lib/entry-points.js b/lib/entry-points.js
index 006389be49..83c0d5891e 100644
--- a/lib/entry-points.js
+++ b/lib/entry-points.js
@@ -147686,7 +147686,7 @@ var semver = __toESM(require_semver2());
 
 // src/api-compatibility.json
 var maximumVersion = "3.22";
-var minimumVersion = "3.16";
+var minimumVersion = "3.17";
 
 // src/json/index.ts
 function parseString(data) {
@@ -153843,9 +153843,9 @@ async function getCombinedTracerConfig(codeql, config) {
 // src/codeql.ts
 var cachedCodeQL = void 0;
 var CODEQL_MINIMUM_VERSION = "2.19.4";
-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 CODEQL_NEXT_MINIMUM_VERSION = "2.20.7";
+var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.16";
+var GHES_MOST_RECENT_DEPRECATION_DATE = "2026-07-01";
 var EXTRACTION_DEBUG_MODE_VERBOSITY = "progress++";
 async function setupCodeQL(toolsInput, apiDetails, tempDir, variant, defaultCliVersion, rawLanguages, useOverlayAwareDefaultCliVersion, features, logger, checkVersion) {
   try {
diff --git a/src/api-compatibility.json b/src/api-compatibility.json
index 435f8f1d6b..7569440194 100644
--- a/src/api-compatibility.json
+++ b/src/api-compatibility.json
@@ -1 +1 @@
-{"maximumVersion": "3.22", "minimumVersion": "3.16"}
+{"maximumVersion": "3.22", "minimumVersion": "3.17"}
diff --git a/src/codeql.ts b/src/codeql.ts
index 5d78337d2e..51fa9600f3 100644
--- a/src/codeql.ts
+++ b/src/codeql.ts
@@ -272,17 +272,17 @@ const CODEQL_MINIMUM_VERSION = "2.19.4";
 /**
  * This version will shortly become the oldest version of CodeQL that the Action will run with.
  */
-const CODEQL_NEXT_MINIMUM_VERSION = "2.19.4";
+const CODEQL_NEXT_MINIMUM_VERSION = "2.20.7";
 
 /**
  * This is the version of GHES that was most recently deprecated.
  */
-const GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.15";
+const GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.16";
 
 /**
  * This is the deprecation date for the version of GHES that was most recently deprecated.
  */
-const GHES_MOST_RECENT_DEPRECATION_DATE = "2026-04-09";
+const GHES_MOST_RECENT_DEPRECATION_DATE = "2026-07-01";
 
 /** The CLI verbosity level to use for extraction in debug mode. */
 const EXTRACTION_DEBUG_MODE_VERBOSITY = "progress++";