This subject has started in an old question (FileMaker Server 16.0.3 Blank WebDirect Login Page)
Problem still is active.
We are unable to reproduce at request, but a number of users are unable to login (getting a blank page after selecting the database). It’s from a variety of OS’es / browsers. They where all able to login the previous server (16), but since we upgraded problems started to appear.
Server: Windows Server 2012R2
FileMaker Server 17.0.2
Downgraded to Java 8.0.1310.11
We downgraded Java to see if this would help, but no luck.