Calibre ebook viewer won't open on Win 10

[timnz]

I've used Calibre for many years. But now the ebook viewer simply won't open. There are no errors displayed. Calibre seems to work fine otherwise (except edit book). I'm using Calibre 4.23 and Windows 10.

If I try to open an epub via Windows Explorer or try to run ebook-viewer.exe directly, I can see the process appear for about one second in the task manager, then disappear, but no window ever opens. If I try to open an epub from Calibre I can see the same thing happen with the calibre-parallel.exe process.

I recently had to update my display drivers, which makes me suspect it has something to do with this issue, but I don't understand the instructions that kovidgoyal linked to.

[pdurrant]

Any ideas, anyone?

[JSWolf]

• If you have Microsoft PowerToys installed, remove them as they interfere with Calibre.
• Update your video driver if possible.
• If you are running on a laptop with dual video chipseets, run Calibre with the other video chipset.
• If you are not running the Microsoft AV, stop the AV you are using.

[theducks]

the OP might try deleting the settings/history file from the configuration folder

BUT
2 different parts failing leads me to believe there is issues creating scratch (temp) files. (both editor and viewer use these)
Security software is the common culprit

[timnz]

Thanks for your suggestions.

Originally Posted by JSWolf

• If you have Microsoft PowerToys installed, remove them as they interfere with Calibre.
• Update your video driver if possible.
• If you are running on a laptop with dual video chipseets, run Calibre with the other video chipset.
• If you are not running the Microsoft AV, stop the AV you are using.

• No PowerToys
• I'd just updated to the latest stable video drivers before this happened
• It's a Desktop PC
• I tried stopping the AV but nothing changed. I'm running Kaspersky Free, which I've been using a long time without any conflicts with Calibre (or anything else, really). I don't think they've had any major updates since Calibre was working a week or so ago.

Originally Posted by theducks

the OP might try deleting the settings/history file from the configuration folder

Which files in particular should I be deleting?

[kovidgoyal]

Open a command prompt run

calibre-debug -w


and post any output you see in the command prompt.

[theducks]

Originally Posted by timnz

Thanks for your suggestions.




Which files in particular should I be deleting?

My surmize was you would have to have 2 different sets (editor and Viewer) corrupted. Not logical. I would expect there would be other issues.
Do provide the debug log (please wrap in [spoiler] tags when posting )

[JSWolf]

One other thing to try is to uninstall Calibre and reinstall. Also, rename your Calibre configuration directory to Calibre.bak and also make a copy of it.

The configuration directory is in %appdata% and the directory is Calibre.

[timnz]

Here's the output from the debugger:

Spoiler:

Turning on automatic hidpi scaling
devicePixelRatio: 1.0
logicalDpi: 96.0 x 96.0
physicalDpi: 95.8113948919 x 95.9160839161
Using calibre Qt style: True
Qt WebEngine resources not found at C:/Program Files/Calibre/app/resources. Trying parent directory...
Qt WebEngine resources not found at C:/Program Files/Calibre/app. Trying application directory...
Qt WebEngine resources not found at C:/Program Files/Calibre. Trying fallback directory... The application MAY NOT work.
[0916/132550.340:ERROR:icu_util.cc(170)] Invalid file descriptor to ICU data received.

Originally Posted by JSWolf

One other thing to try is to uninstall Calibre and reinstall. Also, rename your Calibre configuration directory to Calibre.bak and also make a copy of it.

The configuration directory is in %appdata% and the directory is Calibre.

I'll try this next.

[theducks]

Weird debug listing
the Application folder name is: C:\Program Files\Calibre2

[timnz]

Originally Posted by theducks

Weird debug listing
the Application folder name is: C:\Program Files\Calibre2

That is weird. It's installed to C:\Program Files\Calibre on this PC. I don't have a folder called Calibre2 anywhere at all.

Do you think that's what the problem is?

Is there a way to uninstall and reinstall without losing settings, etc? I just found the answer myself here.

[timnz]

I just uninstalled and reinstalled and it's fixed. It's been installed into the normal Calibre2 folder now too.

I have no idea how I ended up installing it to a different folder, nor why it only recently caused a problem after all these years.

Anyway, thanks a lot everyone for your help.

[theducks]

Wow! AFAIK the folder has been calibre2 for a Decade

Do you use the Advanced/custom mode of the installer (allows override of location or shortcuts)? (There might be a really stale hint in that. I will try that, the next update)

[JSWolf]

Originally Posted by timnz

That is weird. It's installed to C:\Program Files\Calibre on this PC. I don't have a folder called Calibre2 anywhere at all.

Do you think that's what the problem is?

Is there a way to uninstall and reinstall without losing settings, etc? I just found the answer myself here.

I actually think it was more likely something was corrupted and uninstalling removed it.

But anyway, glad Calibre is working once again. I know I'd be lost without it.

[BetterRed]

Originally Posted by theducks

Wow! AFAIK the folder has been calibre2 for a Decade

Do you use the Advanced/custom mode of the installer (allows override of location or shortcuts)? (There might be a really stale hint in that. I will try that, the next update)

Install Advanced has C:\Program Files (X86)\Calibre2\ as the default, note the trailing slash. The Next button has focus, so you have to Tab or Mouse to the Location text box to change it, and then rubout the '/' and the '2'.

Hardly the sort of thing one would do inadvertently. But if you do, the library manager and its viewer still seem to work from C:\Program Files (X86)\Calibre\.

So, something deeper went awry - maybe something to do with the Path environment variable, maybe it had Calibre2 in it - I hate that thing

BR