You are using Java 8, the new version of Ubooquity requires at least Java 17, hence the crash.

Thanks for the feedback everyone ! :)

Could you give me the exact version of Java you use ?

Also, the few log lines after the "A java Exception has occurred" would help too.

As for rar5, support depends on the RAR library used by Ubooquity (Junrar). I'm not sure it will be ever implemented: https://github.com/junrar/junrar/issues/23

Given that RAR files have no advantage over ZIP files for comics, I don't understand why this format is still in use though.

Indeed, thanks !

Should be fixed in the official beta:

https://vaemendis.net/ubooquity/article23/ubooquity-3-beta

I tested the file you sent me: the file is correctly imported and can be read online.

I unfortunately don't know what is the cause of the issue you encounter.

Do you have any error in Ubooquity logs when the "page not found" is displayed ?

If you can send me an example of DJVU file that can't be opened, I'll take a look to try to understand what's wrong. My address: tom 'at' vaemendis.net

The online reader is already usable with DJVU files. 
What issue did you encounter ?

Altso, in current version of Ubooquity (2.x), the Djvu files have to be in the "Books" category.

Yes, the folder pictures were found using a very inefficient way that required several database requests. Now everything is done in a single requests, which completely ignores the user settings regarding sorting. 🤦‍♂️

I'll try to fix that !

Here you go: https://vaemendis.net/ubooquity/downloads/Ubooquity-3.0.0.zip

Java 17 (or more recent) is required.

[EDIT]: you'll find the latest version here: http://vaemendis.net/ubooquity/downloads/

The documentation on the new theme system: https://vaemendis.github.io/ubooquity-doc/pages/theme-creation.html

And a description of the data (variables) made available to the theme, by page: https://vaemendis.github.io/ubooquity-doc/pages/theme-variables-reference.html

The variables are very unlikely to change before the release of the beta.
The default theme will (HTML and definitely CSS), as it is an awful mess in its current state.

Let me know if you have any question !