diff --git a/typo3/sysext/core/Documentation/Changelog/master/Important-90236-RespectExtensionStateExcludeFromUpdatesDuringLanguageUpdates.rst b/typo3/sysext/core/Documentation/Changelog/master/Important-90236-RespectExtensionStateExcludeFromUpdatesDuringLanguageUpdates.rst
new file mode 100644
index 0000000000000000000000000000000000000000..e347e1c8f121445c7c72f7a2394eb92adf6f05dd
--- /dev/null
+++ b/typo3/sysext/core/Documentation/Changelog/master/Important-90236-RespectExtensionStateExcludeFromUpdatesDuringLanguageUpdates.rst
@@ -0,0 +1,18 @@
+.. include:: ../../Includes.txt
+
+========================================================================================
+Important: #90236 - Respect extension state `excludeFromUpdates` during language updates
+========================================================================================
+
+See :issue:`90236`
+
+Description
+===========
+
+If the state property inside :file:`ext_emconf.php` is set to `excludeFromUpdates`,
+the extension will be skipped while updating the language files in the Install Tool.
+
+This setting is especially helpful if you create a custom extension which uses the same extension 
+key as an existing TER extension.
+
+.. index:: Backend, ext:core
diff --git a/typo3/sysext/install/Classes/Service/LanguagePackService.php b/typo3/sysext/install/Classes/Service/LanguagePackService.php
index 1ea8fb9183e6419f9a9dd77e357bf75ec72964f8..275bb8a7f3f866f3a339a86c107060fb4c75395c 100644
--- a/typo3/sysext/install/Classes/Service/LanguagePackService.php
+++ b/typo3/sysext/install/Classes/Service/LanguagePackService.php
@@ -159,6 +159,11 @@ class LanguagePackService implements LoggerAwareInterface
                 $EM_CONF = [];
                 include $path . 'ext_emconf.php';
                 $title = $EM_CONF[$key]['title'] ?? $title;
+
+                $state = $EM_CONF[$key]['state'] ?? '';
+                if ($state === 'excludeFromUpdates') {
+                    continue;
+                }
             }
             $extension = [
                 'key' => $key,