After the update has completed successfully, removed the update-assets directory from the server, cleaned my browser’s cache and successfully logged in the backend, cleaned up the cache as suggested, removed the cache directory in var/cache, the front end still shows a white empty page.
if all you get is a white screen, the error happens very early on, most likely some PHP exception. To see that exception, you need to turn PHP error logging on by adding the following parameters to your php.ini: error_reporting = E_ALL log_errors = On error_log = /home/USER/phperror.log
You can also add display_errors = On to display in the browser, but this will not work if there is some parsing error for example, so by using the error log you will be on the safe side.
I solved my problem. It was a cache management plugin that did this.
Shopware developers state very clearly:
After the update is finished you MUST update all plugins to the latest version!
I am sorry if I wasted your time, thank you @phil for trying to help and I hope this thread helps out anyone looking to find white screen of death solution after an update.