Problem: portal & OX: "405 method not allowed" after upgrade to 5.0-4: wrong redirect to Tornado

After upgrade from 5.0-2 => 5.0-3 => 5.0-4 errata783 the portal and also OX was not working anymore.
After typing the URL https://host.domain.tld the redirect to /univention/portal is not working anymore.
Instead I got the error message mentioned in the title: “405 method not allowed”.
If the complete URL was typed in manually then the portal was accessible.
If I clicked the OX icon, the same error message occurred.

After investigation with curl we came to the result that all was redirected to the Tornado framework which was definitely wrong for …/appsuite.
At the end we found out that the registry entry “portal/paths” was empty with the result that every path was redirected to Tornado.

After that we set it with:

ucr set portal/paths="/univention/portal/, /univention/umc/, /univention/selfservice/"

Then all was fine again.

@Univention: Should this not be checked after installing the Tornado framework?