[TASK] Move legacy Extension installation chapter from Getting started (

#4997)

Replace the outdated "Extension Management" with this more modern chapter

Releases: main, 13.4, 12.4

Co-authored-by: lina.wolf <[email protected]>

Documentation/Administration/Installation/Index.rst

@@ -58,3 +58,4 @@ Installation
     TuneTYPO3
     DeployTYPO3
     LegacyInstallation
+    LegacyExtensionInstallation

Documentation/Administration/Installation/LegacyExtensionInstallation.rst

@@ -0,0 +1,145 @@
+..  include:: /Includes.rst.txt
+
+..  _extensions-legacy-management:
+
+====================================
+Installing Extensions - Legacy Guide
+====================================
+
+.. _extension-manager:
+.. _extension-package-manager:
+.. _extension-install:
+
+Installing an Extension using the Extension Manager
+===================================================
+
+In the backend:
+
+..  rst-class:: bignums
+
+1.  Go to :guilabel:`Admin Tools > Extensions`
+2.  In the Docheader, select :guilabel:`Get Extensions`
+3.  Click :guilabel:`Update now`
+
+    The button is on the top right.
+
+4.  Enter the name of the extension in the search field
+5.  Click on :guilabel:`Go`
+6.  Click on the Action icon on the left for the extension:
+
+    :guilabel:`Import and Install`
+
+    Now the extension is installed, but not activated. To activate:
+
+7.  Choose :guilabel:`Installed Extensions` in the Docheader
+8.  Click on the icon with a :guilabel:`+` sign for your extension
+    in the :guilabel:`A/D` column.
+
+..  _uninstall-extension-without-composer:
+
+Uninstall an Extension Without Composer
+=======================================
+
+If you installed TYPO3 via composer you should uninstall Extensions via composer.
+
+..  _uninstall-extension-without-composer-dependencies:
+
+Check Dependencies
+------------------
+
+First find out, which other extensions and functions of your TYPO3 installation
+are dependent on the extension you want to uninstall. You can find out about
+the dependencies by checking the
+`TYPO3 Extension Repository (TER) <https://extensions.typo3.org/>`__. Look for
+the extension you want to uninstall and the others you have installed. Read
+in each extensions manual the sections 'Dependencies' and 'Reverse dependencies'.
+
+Check whether any referrals have been made to the extension in any setup, config
+or other TypoScript files. Check if you included a plugin from the extension
+in your web site. Think of the results of removing them and finally do it.
+
+If you are working locally or on a test server you might as well try to
+uninstall the extension. The Extension Manager warns you about dependencies that
+are written in an extensions :file:`ext_emconf.php` constraints section.
+Note however that you depend on the extensions developers faithfully noting
+all dependencies in this config file.
+
+If you get an exception and cannot access the Extension Manager anymore because
+of it, you can uninstall / install extensions manually with
+:file:`PackageStates.php` as a last resort, see
+:ref:`uninstall-extension-manually`
+
+..  tip::
+    Be sure not to uninstall extensions by trial and error on production
+    systems, especially not under time pressure.
+
+..  _uninstall-extension-backend:
+
+Uninstall / Deactivate Extension via TYPO3 Backend
+--------------------------------------------------
+
+..  include:: /Images/AutomaticScreenshots/ExtensionManager/UninstallExtension.rst.txt
+
+
+Log into the TYPO3 Backend and open the module
+:guilabel:`Admin tools > Extensions`. From the menu choose
+:guilabel:`Install extensions`. You get an overview about installed extensions.
+
+On the left side you see an icon, which shows the status of each extension,
+and what you can do:
+
+*   Extension Install Icon with plus sign: The extension is
+    not installed. (Click once to install)
+*   Extension Uninstall Icon with minus sign: The extension is installed
+    and running. (Click once to uninstall)
+
+Next to the extension you want to uninstall click on Extension UnInstall Icon.
+After some seconds the icon changes to the grey Extension Install Icon.
+
+..  _remove-extension-backend:
+
+Remove an Extension via the TYPO3 Backend
+--------------------------------------------------
+
+After successfully uninstalling an extension via the Extension Manager you
+can permanently remove the extension by clicking on the waste-basket symbol
+"Remove" beside the extensions entry in the Extension Manager.
+
+..  _uninstall-extension-manually:
+
+Uninstalling an Extension Manually
+----------------------------------
+
+At times an extension causes a problem and the TYPO3 Backend can not
+be opened anymore due to it. In such a case the extension can be uninstalled
+manually. This is not common practise but a last resort.
+
+This can be done by removing the extensions configuration from the file
+:file:`PackageStates.php`
+
+..  rst-class:: bignums
+
+#.  Open the file :file:`typo3conf/PackageStates.php`
+#.  Search for your ext_key in the array.
+
+    ..  code-block:: php
+        :caption: typo3conf/PackageStates.php
+
+        'ext_key' => [
+              'packagePath' => 'typo3conf/ext/ext_key/',
+        ],
+        //...
+
+#. Remove the entry.
+
+..  _remove-extension-manually:
+
+Removing an extension manually
+------------------------------
+
+Removing an extension manually is not common practice and should only be done
+as a last resort. You should only remove an extension that you uninstalled
+successfully. Make a backup first. Then you can permanently remove an extension
+by removing its folder at :file:`typo3conf/ext/[extensionname]`. The
+corresponding database tables can be removed in the
+:guilabel:`Admin Tools > Maintenance > Analyze Database Structure`.

Documentation/Images/AutomaticScreenshots/ExtensionManager/UninstallExtension.rst.txt

@@ -0,0 +1,6 @@
+.. Automatic screenshot: Remove this line if you want to manually change this file
+
+.. figure:: /Images/AutomaticScreenshots/ExtensionManager/UninstallExtension.png
+   :class: with-shadow
+
+   Select "Deactivate" in Extension Manager