When trying to open Sharepoint or OneDrive Sites I receive either an 401 Access denied or a: We are sorry, something went wrong. The issue is actually described in https://support.mozilla.org/en-US/questions/1373433 It seems that it broke again now. There are also other people having this problem: https://www.reddit.com/r/sysadmin/comments/11aot6r/firefox_10280esr_seems_to_have_broken/ If I either clear all cache, active logins and cookies or reload with STRG + F5 it will work temporarily. Setting dom.serviceWorkers.navigationPreload.enabled to False fixes it completely.