customizer not working after update

If your dashboard still works, just disable all plugins and see if problem goes away. Also if your theme is a customized version, temporarily switch to other default WP theme. This is to check if there is any plugin/theme conflicts with the update.

If you can’t login normally, just connect to your server via SFTP and navigate to wp-content/plugins/{plugin-name} and rename all plugins folder name, this is to disable them all. And do the same with your theme if it’s a customized version.

After doing all that and problem still persists, it’s time to do manual re-install.
https://codex.www.ads-software.com/Upgrading_WordPress#Manual_Update

hi paul,
thanks for your fast answer
yes i already disabled all plugins and used another customized theme… and this is what i exactly didi i manually updated wordpress and then i updated the core files again….
still the problem remains

PHP Fatal error: Class ‘WP_Customize_Filter_Setting’ not found in /…/…../…/wp-includes/class-wp-customize-manager.php on line 4854

Did you build the site by yourself. If someone did the job for you there is a chance that he/she put some plugins in mu folder https://codex.www.ads-software.com/Must_Use_Plugins

Check wp-config.php see if there is any reference to mu plugin, if exists you will see the folder path, navigate to that folder and remove all plugin in there (make a backup copy first).

With a fresh WP install (manual update that’s completed), fresh un-modified WP’s default theme, without any plugin, your site should not display that error. If it still has that error, contact your hosting provider. I recently have this kind of problem with one of my client site and it runs on a very cheap shared host, I called the company and they resolved it for me.

ok now i reinstalled the english core version and voila everything is fine ….
so maybe the german one was buggy
thanks paul for your reply

Good to hear your site is okay now ??