ok, thanks. I think i will do that...

Compression version 4 fails too... :(

Update: renaming cbr to cbz results in an error after restarting ubooquity. Behaviour here is right.

But still some cbrs dont show up like mentioned before.

Logs here:

20200529 16:32:28 [Scanner thread] INFO com.ubooquity.b.d - Reading metadata of comic file: /comics/Lucky Luke/Zack Album - Lucky Luke 01-14/Zack Album 03 - Lucky Luke - und der Großfürst.cbr
20200529 16:32:28 [Scanner thread] WARN com.ubooquity.f.a - Could not open file: /comics/Lucky Luke/Zack Album - Lucky Luke 01-14/Zack Album 03 - Lucky Luke - und der Großfürst.cbr
com.github.junrar.exception.RarException: notRarArchive
   at com.ubooquity.fileformat.cbr.a.a(SourceFile:39) ~[Ubooquity.jar:2.1.2]
   at com.ubooquity.f.a.b(SourceFile:73) ~[Ubooquity.jar:2.1.2]
   at com.ubooquity.f.a.a(SourceFile:22) ~[Ubooquity.jar:2.1.2]
   at com.ubooquity.b.d.a(SourceFile:71) ~[Ubooquity.jar:2.1.2]
   at com.ubooquity.data.feeder.a.b(SourceFile:531) ~[Ubooquity.jar:2.1.2]
   at com.ubooquity.data.feeder.a.b(SourceFile:468) ~[Ubooquity.jar:2.1.2]
   at com.ubooquity.data.feeder.a.b(SourceFile:112) ~[Ubooquity.jar:2.1.2]
   at java.base/java.lang.Thread.run(Thread.java:832) ~[na:na]
20200529 16:32:28 [Scanner thread] WARN com.ubooquity.f.a - Failed to read file, checking potential extension mistake (cbz/cbr) for: /comics/Lucky Luke/Zack Album - Lucky Luke 01-14/Zack Album 03 - Lucky Luke - und der Großfürst.cbr
20200529 16:32:28 [Scanner thread] INFO com.ubooquity.f.a - File type is ZIP (cbz)

real rar file: compressed by me with rar a XIII - 16 - Operation Montecristo.cbr ./XIII - 16 - Operation Montecristo/

20200529 16:32:30 [Scanner thread] INFO com.ubooquity.b.d - Reading metadata of comic file: /comics/XIII 1-24 +1/XIII - 16 - Operation Montecristo.cbr
20200529 16:32:30 [Scanner thread] WARN com.ubooquity.f.a - Could not open file: /comics/XIII 1-24 +1/XIII - 16 - Operation Montecristo.cbr
com.github.junrar.exception.RarException: notRarArchive
   at com.ubooquity.fileformat.cbr.a.a(SourceFile:39) ~[Ubooquity.jar:2.1.2]
   at com.ubooquity.f.a.b(SourceFile:73) ~[Ubooquity.jar:2.1.2]
   at com.ubooquity.f.a.a(SourceFile:22) ~[Ubooquity.jar:2.1.2]
   at com.ubooquity.b.d.a(SourceFile:71) ~[Ubooquity.jar:2.1.2]
   at com.ubooquity.data.feeder.a.b(SourceFile:531) ~[Ubooquity.jar:2.1.2]
   at com.ubooquity.data.feeder.a.b(SourceFile:468) ~[Ubooquity.jar:2.1.2]
   at com.ubooquity.data.feeder.a.b(SourceFile:112) ~[Ubooquity.jar:2.1.2]
   at java.base/java.lang.Thread.run(Thread.java:832) ~[na:na]
20200529 16:32:30 [Scanner thread] WARN com.ubooquity.f.a - Failed to read file, checking potential extension mistake (cbz/cbr) for: /comics/XIII 1-24 +1/XIII - 16 - Operation Montecristo.cbr
20200529 16:32:30 [Scanner thread] INFO com.ubooquity.f.a - File type is RAR (cbr)
20200529 16:32:30 [Scanner thread] INFO com.ubooquity.f.a - No extension mistake detected.
20200529 16:32:30 [Scanner thread] WARN com.ubooquity.f.a - Could not open file: /comics/XIII 1-24 +1/XIII - 16 - Operation Montecristo.cbr

PS: Im running ubooquity actually with openjdk14, same error with openjdk8.