Hello,
I've just installed APEX 5.1+ords.3.0.9.348.07.16 deployed to TomCat 8.0.36 (OS is OpenSUSE Leap 42.2 if it's important). Both services (oracle-xe and tomcat) are started automatically by systemd but when I try to login to APEX, I get the message
404 Not Found
The request could not be mapped to any database. Check the request URL is correct, and that URL to database mappings have been correctly configured
The problem is solved by simply restarting TomCat. Then after a successfull connection I also tried to stop the running database with TC running and to a connection attempt to the stopped DB backend it responded
500 Internal Server Error
but was able to connect again as soon as the DB was up.
So I assume when TomCat starts sooner than oracle-xe service, ORDS cannot connect and does not make any other attempts to establish connection. Of course it would be possible to make sure that Oracle starts before TomCat, elaborating with systemd is annoying and I have no idea how to do the same on Windows, but since I haven't had any such problems with any of the previous ORDS releases, maybe someone from the development team could take a look at it if anything has changed and eventually modify this behaviour (I'm not saying to fix it because it's not exactly broken).
If it was tough to reproduce, I could share the entire VM image.
Regards
Pavel