[lkstrummer]

Opening new epubs loads the "Preparing book for first read, please wait" message on the e-book viewer. However, the viewer hangs forever and the book doesn't open. No error message is generated either as it hangs indefinitely.

Previously opened epubs will still open as usual unless there's another instance of the e-book viewer trying to open another epub for the first time (and hanging indefinitely). Two or more instances of epubs that have previously been opened will still continue to open normally. The process is only disrupted by an instance of the e-book viewer preparing an epub for the first read and hanging.

In the case of the previously opened epub that won't open with an instance of the e-book viewer that is hanging on a new book, an error message is generated. The error message:

WindowsError: [Error 32] The process cannot access the file because it is being used by another process.: u'C:\\Users\\xxxxx\\AppData\\Local\\calibre-cache\\ev2\\metadata.json'

I've searched for a solution to this error and was pointed towards making an exception to the cache folder in my antivirus (avast). I've done so and I also turned off Avast to both repair and reinstall the latest calibre 5.22.1. However, this error with the e-book viewer persists.