Hello!

I have an epub and Okular can read it without any issues. I add some annotations and want to save them with the "Okular document archive" file format. But when I open these files, Okular says "Error while opening EPub document."

So at the moment I can not add any annotations, because I am not able to save them.

Can somebody help?

For me the issue was the .okular file extension was not added at save. As soon as I added the file extension via renaming the file I was able to open it.