How to upgrade MediaWiki to 1.40 version

Link to page for web updating - your_site_url/mw-config/index.php

If your version older then 1.35 version, then firstly update to 1.35 version. Only after that update to 1.40 version. Otherwise, it can brake you data in DB.

If you see 500 error after updating - check permissions for folders: cache, vendor, skins, includes. For changing permission use command:

chmod -R 777 ./cache

If you see another errors on the pages, try to update extensions.

To fix Logo after updating: need to change $wgLogo to $wgLogos.

Before:  $wgLogo = "$wgScriptPath/resources/assets/logo.png";

After:  $wgLogos = [
   '1x' => "$wgScriptPath/resources/assets/logo.png",
   '1.5x' => "$wgScriptPath/resources/assets/logo.png",
   '2x' => "$wgScriptPath/resources/assets/logo.png",
   'svg' => "$wgScriptPath/resources/assets/logo.png"
];