Hello, it seems there is an issue with an automatic update. After update at 2020-03-21 (not updated since 2019-03-01) Website is accessible, but backend (/backend) is not accessable: Shows "File not found." network response 404 (and after going to backend, website throws 403 now since the token is updated) How to fix this? Website worked fine since the automatic update.

check the logs in /storage/logs/system.log

Log file is old. Some non related errors

check file permissions maybe?

Never mind, had to rebuild everything. This time composer way. Really hard to manage without knowing what update did.