Calibre won't run anymore on Windows 10

[GonkZonk]

Hi, like the title says neither the main program, ebook editor or viewer will start for me anymore after several years of using this program.

• It won't start in safe mode
• It briefly appears in task manager but then goes away
• I've tried reinstalling it, removing the configuration files in %appdata% and reinstalling it.
• I use windows defender with no other antiviruses apart from malwarebytes free
• It won't run with admin rights
• I downloaded it twice and it results in the same problem

here's a debug log:

C:\Users\gonkzonk>calibre-debug -g
calibre 5.5  embedded-python: True is64bit: False
Windows-10-10.0.18362 Windows ('32bit', 'WindowsPE')
32bit process running on 64bit windows
('Windows', '10', '10.0.18362')
Python 3.8.5
Windows: ('10', '10.0.18362', '', 'Multiprocessor Free')
Interface language: None
Not controlling automatic hidpi scaling
Warning: QT_DEVICE_PIXEL_RATIO is deprecated. Instead use:
   QT_AUTO_SCREEN_SCALE_FACTOR to enable platform plugin controlled per-screen factors.
   QT_SCREEN_SCALE_FACTORS to set per-screen DPI.
   QT_SCALE_FACTOR to set the application global scale factor.

I tried some solutions found in other threads but none of them helped. I don't know what else to do to fix this.
thanks

[kovidgoyal]

You appear to have a QT environent variable set. unset it.

[GonkZonk]

Originally Posted by kovidgoyal

You appear to have a QT environent variable set. unset it.

Thanks for replying. That got rid of the QT error but the program still won't start.

[kovidgoyal]

And whats the full debug output now? and the exit code of calibre-debug?

[GonkZonk]

It's working now! I just rebooted and reinstalled it and it started working. Thanks for your help sir

[MusicalBox]

Hi.
I have the same problem. Using Windows 10 as well

I was using my previous version of Calibre and after closing the program I downloaded and installed the latest version. Trying to launch from the desktop icon or from the Start panel had no effect. Calibre wouldn't start.

• I ran the calibre-5.5.0.msi file again and used the "Repair" option... but no luck with that.
• I tried to reinstall it after rebooting (like GonkZonk did) but that didn't work for me either.

I'd show you a debug log too, but I don't know where to get it.

Maybe it's a totally different thing, but I remember having the same issue with another program a while ago (couple of years maybe). It would only start to launch after modifying something in the (I think) program's desktop icon Properties panel. Or something like that... I don't remember what the procedure was exactly... So I just mention it in case that could help ring a bell to someone

I hope you can help me solve this problem. in advance

[MusicalBox]

***EDIT OF MY PREVIOUS MESSAGE***

I went to the download page to get an older version that I could use while I wait for a solution.

So I clicked on "Previous releases of calibre are available here" and I found out there is a 64-bit version of 5.5.0 there. On the main Windows download page, the Download Calibre link automatically sends the 32-bit file.

I installed this 64-bit version of 5.5.0 and Calibre works perfectly now

[davidfor]

Originally Posted by MusicalBox

***EDIT OF MY PREVIOUS MESSAGE***

I went to the download page to get an older version that I could use while I wait for a solution.

So I clicked on "Previous releases of calibre are available here" and I found out there is a 64-bit version of 5.5.0 there. On the main Windows download page, the Download Calibre link automatically sends the 32-bit file.

I installed this 64-bit version of 5.5.0 and Calibre works perfectly now

The download page shows both "Windows" and "Windows 64bit". The first one is the 32bit version. If you use calibre to go to the download page when a new version is presented, it will take you to the page for the version you have. The change between 32bit and 64bit needs an uninstall first. Which is why you aren't automatically taken to the 64bit version. It might make sense to have a note suggesting to change to the 64 bit version.

[MusicalBox]

Originally Posted by davidfor

It might make sense to have a note suggesting to change to the 64 bit version.

Agreed