Hello I have found I have problems when the filename/pathname is too long.

I get a windows: Error opening comic
Format not supported

It happen with files with long path or name. For example.
L:\BD\[ES]\20210323\[Marvel]The.Ultimates[Completo][Todo.Ultimates][Forum.Panini][Comic][Spanish-Espanol][CRG]\05 Especiales Ultimates[Completo][Pesadilla Secreto Visiones][Panini][Comic][Spanish-Espanol][CRG]\Especial Ultimates 1 & X-Men -1234567890-1234.cbr

This file generate a problem.
If I delete the las 4 digit the viewer works and everything is OK

Windows has its limitations regarding file paths lengths.

I created that path, and I put a file inside it, then I tried to rename the file with Especial Ultimates 1 & X-Men -1234567890-1234.cbr

This is the result, as you can see Windows 11 won't let me add more characters...

I understand there must be some kind of limitation in the path in windows.
But I can tell you I am working with this longer filenames and they are working with other apps (for example comics viewer COVER)
In the following links you can see al the test I do.
First I have modify a little the path and the final path is
L:\BD\[ES]\20210323\[Marvel]The.Ultimates[Completo][Todo.Ultimates][Forum.Panini][Comic][Spanish-Espanol][CRG]\05 Especiales Ultimates[Completo][Pesadilla Secreto Visiones][Panini][CRG]\Especial Ultimates 1 & X-Men -1234567890-1234567890-1234567890-1234567890.cbr

You can see it on my windows explorer
https://drive.google.com/file/d/1Y5q3vSi7phb245DqoRm-iQJ5waJ8g8i8/view?usp=drive_link

You can have the error I get with YACREADER viewer
https://drive.google.com/file/d/1qt53mlO-p7Rt9elPASF9EEv-_OAqwdYe/view?usp=drive_link

You have a successfull view with COVER viewer
[img size=100-300]drive.google.com/file/d/1qm2D_YBvr8RQs6n.../view?usp=drive_link[/img]

You have a successfull view with SUMATRA viewer
https://drive.google.com/file/d/1Tl_VNJ-c74jfJeln-3FNPI6DpbxpaUTl/view?usp=drive_link

Hope all this may help to find possible problem
By the way, I am using windows 11 Pro
10.0.22631 Build 22631
x64-based PC

Windows itself tries to actively prevent it…

I’ll look into it but I am not considering it a bug, so I’ll give it low priority for now…