Calibre 7.21 won't start on Win 10

[gavinallen50]

I haven't used it for a few weeks but Calibre has suddenly stopped working.

I haven't installed anything new recently, just the usual windows updates. The is no error in the Event Viewer.

I have tested the following:

Normal - doesn't start
Normal (with all services and startup apps disabled) - doesn't start
Safe Mode - works

The only way I've managed to get it to start is if I disable my Display Adapter in Device Manager...then it starts fine.

I've tried updating my graphics driver to the latest version with no effect. I've also tried old version of Calibre with no effect.

Here is the output from calibre-debug:

with display adapter disabled Calibre opens successfully:

C:\WINDOWS\system32>calibre-debug -g
calibre 7.21 embedded-python: True
Windows-10-10.0.19045-SP0 Windows ('64bit', 'WindowsPE')
('Windows', '10', '10.0.19045')
Python 3.11.5
Windows: ('10', '10.0.19045', 'SP0', 'Multiprocessor Free')
Interface language: None
EXE path: C:\Program Files\Calibre2\calibre-debug.exe
Successfully initialized third party plugins:
QPA platform: windows
devicePixelRatio: 1.0
logicalDpi: 96.0 x 96.0
physicalDpi: 108.91792294807368 x 108.85714285714285
Using calibre Qt style: False
[0.00] Starting up...
[0.00] Showing splash screen...
[1.22] splash screen shown
[1.22] Initializing db...
[2.27] db initialized
[2.27] Constructing main UI...
[4.08] GUI main window shown
[4.17] main UI initialized...
[4.17] Hiding splash screen
[4.17] splash screen hidden
[4.17] Started up in 4.17 seconds with 10826 books


with display adapter enabled I get this output but nothing else:

C:\WINDOWS\system32>calibre-debug -g
calibre 7.21 embedded-python: True
Windows-10-10.0.19045-SP0 Windows ('64bit', 'WindowsPE')
('Windows', '10', '10.0.19045')
Python 3.11.5
Windows: ('10', '10.0.19045', 'SP0', 'Multiprocessor Free')
Interface language: None
EXE path: C:\Program Files\Calibre2\calibre-debug.exe
Successfully initialized third party plugins:





Thanks.

[BetterRed]

Try the suggestion in this post ==>> https://www.mobileread.com/forums/sh...1&postcount=15

BR

[JSWolf]

Could it be the GUI is off the screen? If that is the case, then try the following to test it out.

Go to the settings directory which is C:\Users\XXXX\AppData\Roaming\Calibre and rename the file gui.json to gui.json.bak. Then run calibre again. If it shows up, that means the gui was off screen. BTW, XXXX is your Windows account directory name.

[kovidgoyal]

Sounds like Qt doesnt like your display driver. Or some other software on your system is interfering since you say it works in safe mode. Try disabling startup services one by one till you find the culprit.

[fireffox]

I have the same problem. I've tried to change environment variable and disabling startup services. Nothing helps...

[theducks]

How about those with this fail mentioning What Display chip/board and what Driver is installed.

To quote my CPO: "broken is not a trouble call out".
It is your system. Only YOU know what is in YOUR systems box.

I have Dell Optiplex 780 With a basic (not a gaming) Radeon card that the Viewer goes into infinite Preparing... . (The toc appears greyed out) The Library loads and the editor (includes preview) works

[JSWolf]

Originally Posted by fireffox

I have the same problem. I've tried to change environment variable and disabling startup services. Nothing helps...

Try safe mode.

[chaley]

Originally Posted by JSWolf

Try safe mode.

The OP said it works in safe mode. That is why Kovid answered as he did in post #4.

[gavinallen50]

Thanks for all the replies.

I have tried Safe Mode (which worked), but I've also tried disabling all services and startup apps (which didn't).

I had seen the suggestion to set QTWEBENGINE_CHROMIUM_FLAGS before, but I thought that was only for the book viewer so I didn't try...I will try it.

The window is not showing off the screen.

The graphics card is an old Zotac GeForce GTX 1060 and I'm using the following driver (though I have also tried an old one from earlier in the year when Calibre was working):
GeForce Game Ready Driver - WHQL
Driver Version: 566.03 - Release Date: 2024 October 22

So far the only 2 things that have worked for me are Safe Mode and disabling the display adapter (which is my current solution as it can be done with Powershell very quickly).


Thanks again, and thank you Kovid for an excellent application.

[fireffox]

Originally Posted by gavinallen50

So far the only 2 things that have worked for me are Safe Mode and disabling the display adapter (which is my current solution as it can be done with Powershell very quickly).

When you disabling your display adapter You don't have blank screen?
Where did You get the script?

[gbm]

https://doc.qt.io/qt-6/qtwebengine-debugging.html


bernie

Originally Posted by fireffox

When you disabling your display adapter You don't have blank screen?
Where did You get the script?

[gavinallen50]

Originally Posted by fireffox

When you disabling your display adapter You don't have blank screen?
Where did You get the script?

I run this in Powershell, as Admin....
To open Calibre:

# Get the display adapter
$adapter = Get-PnpDevice -FriendlyName "NVIDIA GeForce GTX 1060 6GB"

# Disable the display adapter
Disable-PnpDevice -InstanceId $adapter.InstanceId

& "C:\Program Files\Calibre2\Calibre.exe"

To restart the display adapter:

# Get the display adapter
$adapter = Get-PnpDevice -FriendlyName "NVIDIA GeForce GTX 1060 6GB"

# Enable the display adapter
Enable-PnpDevice -InstanceId $adapter.InstanceId

• You'll need to update the name of the display adapter with the name you'll find in the Device Manager
• You'll need to update the path to the Calibre exe if it's not in the standard location
• Don't forget to run as admin otherwise it won't work

[BetterRed]

Running Windows calibre as administrator has been known to cause problems. The one instance I do recall resulted in drag-drop events being ignored… there may have been others.

Apps Don’t Open Unless Run as Administrator » Winhelponline

A third-party tuning program installed on the computer may have blocked the apps from running unelevated. CCleaner Professional, AVG TuneUp, and Avast Cleanup Premium are some examples. These programs have a feature that puts resource-hungry apps into sleep or snooze mode.

IMO - programs such as those mentioned are best avoided.

BR