Ubooquity 3.0.2 pdf errors

I am using now since some months the 3.0.2 on freebsd 13 and encountered some problems with PDFs: Some of the newly imported pdfs dont show the title-page, only the white standard-symbol. When i try to open them i get a "Page not found".

Download works.

Here the logs:

20240429 18:32:26 [qtp1569371800-602] WARN o.e.j.server.handler.ContextHandler - Unimplemented getRequestCharacterEncoding() - use org.eclipse.jetty.servlet.ServletContextHandler
20240429 18:32:26 [qtp1569371800-545] INFO com.ubooquity.provider.e.a - Someone is reading Elektrotechnik 2 - Manfred Albach
20240429 18:32:28 [qtp1569371800-545] ERROR com.ubooquity.f.a - Could not get image from file: /mnt//Manfred Albach/Elektrotechnik 2 (2378)/Elektrotechnik 2 - Manfred Albach.pdf
20240429 18:32:28 [qtp1569371800-545] WARN com.ubooquity.provider.e.a - Could not extract page 0 from document /mnt//Manfred Albach/Elektrotechnik 2 (2378)/Elektrotechnik 2 - Manfred Albach.pdf (NullPointerException)
20240429 18:32:49 [qtp1569371800-629] WARN o.e.j.server.handler.ContextHandler - Unimplemented getRequestCharacterEncoding() - use org.eclipse.jetty.servlet.ServletContextHandler
20240429 18:32:49 [qtp1569371800-602] INFO com.ubooquity.provider.e.a - Someone is reading Elektronische Schaltungstechnik - Harald Hartl
20240429 18:32:50 [qtp1569371800-602] ERROR com.ubooquity.f.a - Could not get image from file: /mnt//Harald Hartl/Elektronische Schaltungstechnik (11)/Elektronische Schaltungstechnik - Harald Hartl.pdf
20240429 18:32:50 [qtp1569371800-602] WARN com.ubooquity.provider.e.a - Could not extract page 0 from document /mnt//Harald Hartl/Elektronische Schaltungstechnik (11)/Elektronische Schaltungstechnik - Harald Hartl.pdf (NullPointerException)

I hope, that helps.

Ah, other error: When i click on the upper left ubooquity-symbol, it redirects to servername:2203; i have changed that ports to 80 for the library and 81 for admin. I have changed that value in the preferences-2.json as well, but no change in behaviour.

Edit: Some of the older pdfs show the same error; they were shown with their respect first page in the 2.1.2.

Thanks