diff --git a/typo3/sysext/core/Classes/TypoScript/TemplateService.php b/typo3/sysext/core/Classes/TypoScript/TemplateService.php
index f43210bc552ff6f6f6450b8f9025a4030623244a..b89e39aacb2276c6280700058ff41ed4fa67929f 100644
--- a/typo3/sysext/core/Classes/TypoScript/TemplateService.php
+++ b/typo3/sysext/core/Classes/TypoScript/TemplateService.php
@@ -690,38 +690,6 @@ class TemplateService
         }
     }
 
-    /**
-     * This function can be used to update the data of the current rootLine
-     * e.g. when a different language is used.
-     *
-     * This function must not be used if there are different pages in the
-     * rootline as before!
-     *
-     * @param array $fullRootLine Array containing the FULL rootline (up to the TYPO3 root)
-     * @throws \RuntimeException If the given $fullRootLine does not contain all pages that are in the current template rootline
-     */
-    public function updateRootlineData($fullRootLine)
-    {
-        if (!is_array($this->rootLine) || empty($this->rootLine)) {
-            return;
-        }
-
-        $fullRootLineByUid = [];
-        foreach ($fullRootLine as $rootLineData) {
-            $fullRootLineByUid[$rootLineData['uid']] = $rootLineData;
-        }
-
-        foreach ($this->rootLine as $level => $dataArray) {
-            $currentUid = $dataArray['uid'];
-
-            if (!array_key_exists($currentUid, $fullRootLineByUid)) {
-                throw new \RuntimeException(sprintf('The full rootLine does not contain data for the page with the uid %d that is contained in the template rootline.', $currentUid), 1370419654);
-            }
-
-            $this->rootLine[$level] = $fullRootLineByUid[$currentUid];
-        }
-    }
-
     /**
      * Includes static template files (from extensions) for the input template record row.
      *
diff --git a/typo3/sysext/core/Documentation/Changelog/12.0/Breaking-96351-UnusedTemplateService-updateRootlineDataMethodRemoved.rst b/typo3/sysext/core/Documentation/Changelog/12.0/Breaking-96351-UnusedTemplateService-updateRootlineDataMethodRemoved.rst
new file mode 100644
index 0000000000000000000000000000000000000000..6aa210cd74cfdcfdbbbdf7ec40b347c46b3713b1
--- /dev/null
+++ b/typo3/sysext/core/Documentation/Changelog/12.0/Breaking-96351-UnusedTemplateService-updateRootlineDataMethodRemoved.rst
@@ -0,0 +1,43 @@
+.. include:: ../../Includes.txt
+
+============================================================================
+Breaking: #96351 - Unused TemplateService->updateRootlineData method removed
+============================================================================
+
+See :issue:`96351`
+
+Description
+===========
+
+The PHP method `TemplateService->updateRootlineData()` is removed.
+
+It was used as a workaround to update the fetched Rootline with
+translated pages until TYPO3 v10. This was necessary because the
+TypoScript information contained the language information, and
+then the page translations were loaded accordingly.
+
+Since TYPO3 v11 the language is resolved earlier, at the same
+time as the page ID, and the mechanism became obsolete.
+
+
+Impact
+======
+
+Calling the method in PHP will throw a fatal PHP error, as the method does not exist anymore.
+
+
+Affected Installations
+======================
+
+TYPO3 installations, mainly legacy installations with legacy
+extensions using this method to boot up their own TypoScript
+parsing.
+
+
+Migration
+=========
+
+Calling this method is not needed anymore and can be removed
+from the affected code.
+
+.. index:: Frontend, PHP-API, FullyScanned, ext:core
\ No newline at end of file
diff --git a/typo3/sysext/core/Tests/Unit/TypoScript/TemplateServiceTest.php b/typo3/sysext/core/Tests/Unit/TypoScript/TemplateServiceTest.php
index 56352af8fef3cc23b0870911712a82d5e098e6c6..178b15a4d2f21cb0dac89aa0811d46dbc5e88b43 100644
--- a/typo3/sysext/core/Tests/Unit/TypoScript/TemplateServiceTest.php
+++ b/typo3/sysext/core/Tests/Unit/TypoScript/TemplateServiceTest.php
@@ -153,52 +153,4 @@ class TemplateServiceTest extends UnitTestCase
             $this->templateService->config
         );
     }
-
-    /**
-     * @test
-     */
-    public function updateRootlineDataOverwritesOwnArrayData(): void
-    {
-        $originalRootline = [
-            0 => ['uid' => 2, 'title' => 'originalTitle'],
-            1 => ['uid' => 3, 'title' => 'originalTitle2'],
-        ];
-
-        $updatedRootline = [
-            0 => ['uid' => 1, 'title' => 'newTitle'],
-            1 => ['uid' => 2, 'title' => 'newTitle2'],
-            2 => ['uid' => 3, 'title' => 'newTitle3'],
-        ];
-
-        $expectedRootline = [
-            0 => ['uid' => 2, 'title' => 'newTitle2'],
-            1 => ['uid' => 3, 'title' => 'newTitle3'],
-        ];
-
-        $this->templateService->rootLine = $originalRootline;
-        $this->templateService->updateRootlineData($updatedRootline);
-        self::assertEquals($expectedRootline, $this->templateService->rootLine);
-    }
-
-    /**
-     * @test
-     */
-    public function updateRootlineDataWithInvalidNewRootlineThrowsException(): void
-    {
-        $originalRootline = [
-            0 => ['uid' => 2, 'title' => 'originalTitle'],
-            1 => ['uid' => 3, 'title' => 'originalTitle2'],
-        ];
-
-        $newInvalidRootline = [
-            0 => ['uid' => 1, 'title' => 'newTitle'],
-            1 => ['uid' => 2, 'title' => 'newTitle2'],
-        ];
-
-        $this->expectException(\RuntimeException::class);
-        $this->expectExceptionCode(1370419654);
-
-        $this->templateService->rootLine = $originalRootline;
-        $this->templateService->updateRootlineData($newInvalidRootline);
-    }
 }
diff --git a/typo3/sysext/install/Configuration/ExtensionScanner/Php/MethodCallMatcher.php b/typo3/sysext/install/Configuration/ExtensionScanner/Php/MethodCallMatcher.php
index f9d55e2e193030a20fc244a657282554a65c77c0..6b3ad773e82944e9e319c25a3d15ccba81be9e3c 100644
--- a/typo3/sysext/install/Configuration/ExtensionScanner/Php/MethodCallMatcher.php
+++ b/typo3/sysext/install/Configuration/ExtensionScanner/Php/MethodCallMatcher.php
@@ -5084,4 +5084,11 @@ return [
             'Breaking-96107-DeprecatedFunctionalityRemoved.rst',
         ],
     ],
+    'TYPO3\CMS\Core\TypoScript\TemplateService->updateRootlineData' => [
+        'numberOfMandatoryArguments' => 1,
+        'maximumNumberOfArguments' => 1,
+        'restFiles' => [
+            'Breaking-96351-UnusedTemplateService-updateRootlineDataMethodRemoved.rst',
+        ],
+    ],
 ];