[BetterRed]

Originally Posted by yathribjr

I forgot to mention that I am now using "Windows 10 Creators Update" (v. 1703) 64 bit.

Among its new media features, it adds .epub file reading capabilities to Windows via the Microsoft Edge browser. This may be helping mess up the .epub file associations.

@yathripjr - I doubt it, but here's a link on How to ditch Microsoft Edge as your default PDF reader on Windows 10. One would hope the same techniques would work for EPUB.

If that doesn't solve your problems you could try one or all of the following:-

• running calibre-debug --default-programs unregister before you install version 3.4
• run sfc /scannow
• do an Repair Install of Windows 10

But I don't know if any one of those or even all three will solve your problems. Maybe you need to do a Windows Refresh or Windows Reset and a reinstall everything else.

Or you could do what I've done:-

• remove all traces of calibre from Windows file associations with the calibre debug command I gave you,
• set the requisite environment variable I gave you,
• explicitly create the associations you need - in my case I associate the calibre viewer and editor with ePub - period.

Calibre is by no means the only program for which I've had to do something similar over the past 20+ years.

BR