unexpected log out & error for ver 7.9.9 using iis server and mssql 2016 on windows 10 64 bit , when press refresh (F5) microsoft edge the system returned to previous situation that logged out and php 7.1
when adding new custome field the system freezed until F5 refresh
using php7.1
It’s the first time I’ve seen a bug report with this structure:
problem, unspecified error, suite version, web server version, database version, os version, first step to reproduce, browser version, effect, php version, which screen, further steps, php version again.
BRILLIANT! Have you had any sleep lately? 
My advice is to check your logs.
And now I’m going to sleep.