The program does not launch the interface.

Frantishek · 11-02-2025, 03:02 AM

Unexpectedly, after restarting the computer (Windows 10) and with no device connected, the program stopped launching.
The interface initialization window appears. In Task Manager, there is a running process called - calibre worker process.
The previous session of the program was closed correctly by clicking Exit.

What has been done to try to fix this (the hanging process is terminated manually):

1. Reinstalled the latest portable version of the program.
2. Moved the portable program folder to the root directory of the disk.
Neither helped.

What should I do next? (It’s very important not to lose the settings — a lot has been customized in the interface and many plugins have been installed)
There were many plugins installed, but the program worked fine with them for more than ten days and launched successfully after each closing.

Possible cause: around the same time, I configured another program and changed the Python environment in the system (in case that might be related).

kovidgoyal · 11-02-2025, 07:28 AM

https://manual.calibre-ebook.com/faq...ing-on-windows

tnavarra · 11-10-2025, 03:17 PM

This problem started about a month ago after a windows update. I tried rolling Calibre back to the 8.13 version. I have rebooted into safe mode and calibre still does not do anything beyond the splash screen.

I have checked the task manager and no calibre processes are running

Need some help to get this going. Getting to a critical stage.

Thanks in advance

Ran the Calibre debug command and this is what I get (windows specs are below):

calibre 8.14 embedded-python: True
Windows-10-10.0.26200-SP0 Windows ('64bit', 'WindowsPE')
('Windows', '10', '10.0.26200')
Python 3.11.14
Windows: ('10', '10.0.26200', 'SP0', 'Multiprocessor Free')
Interface language: None
EXE path: C:\Program Files\Calibre2\calibre-debug.exe
Successfully initialized third party plugins: Gather KFX-ZIP (from KFX Input) (2, 26, 2) && DeDRM (10, 0, 3) && Package KFX (from KFX Input) (2, 26, 2) && BookFusion Plugin (0, 8, 1) && FanFicFare (4, 49, 0) && Goodreads (1, 8, 3) && KFX metadata reader (from KFX Input) (2, 26, 2) && From KFX (2, 26, 2) && KFX Input (2, 26, 2) && Set KFX metadata (from KFX Output) (2, 18, 0) && KFX Output (2, 18, 0)
QPA platform: windows
devicePixelRatio: 1.0
logicalDpi: 96.0 x 96.0
physicalDpi: 102.45378151260503 x 102.35820895522387
ApplicationPaletteChange event ignored
Using calibre Qt style: True
ApplicationPaletteChange event received
[0.00] Starting up...
[0.00] Showing splash screen...
[1.19] splash screen shown
[1.19] Initializing db...

Windows Version:

Edition Windows 11 Pro
Version 25H2
Installed on ‎12/‎4/‎2024
OS build 26200.7019
Experience Windows Feature Experience Pack 1000.26100.265.0

kovidgoyal · Yesterday, 12:28 AM

That debug log indicates something is blocking calibre at the database initialization stage. Typical culprits are security/antivirus programs. Try excluding the calibre library folder from these and or disable them temporarily to debug.

tnavarra · Yesterday, 01:53 AM

Quote:

Originally Posted by kovidgoyal

That debug log indicates something is blocking calibre at the database initialization stage. Typical culprits are security/antivirus programs. Try excluding the calibre library folder from these and or disable them temporarily to debug.

I uninstalled AVG and Malware bytes. Still has not worked. Uninstalled and then re-installed calibre 8.14. Still no good.

Not sure the next step. Any help appreciated

DNSB · Yesterday, 04:12 AM

Have you tried starting Windows in safe mode and then launching calibre? This should eliminate a lot of the programs that could be interfering with calibre.

DiapDealer · Yesterday, 01:21 PM

Quote:

Originally Posted by tnavarra

I uninstalled AVG and Malware bytes. Still has not worked. Uninstalled and then re-installed calibre 8.14. Still no good.

Not sure the next step. Any help appreciated

Have you tried exempting the folder Kovid mentioned above from Windows Defender? It's not only 3rd-party antivirus that can cause problems.

tnavarra · Yesterday, 02:59 PM

Thanks for your help!

I got it fixed. I hade to delete the old DB file and then rebuild the database. It worked.

My thinking was that since it was hanging on the open database step, perhaps there is something wring with the database. Moved the old ones to a new directory and the program was able to open with a blank library. Rebuilt the DB and they all 5600+books came back in. Just took a few minutes. After the rebuilding, I then closed the program and then re-opened it. Worked perfect.

I had started it in safe-mode before I started uninstalling AVG and Malwarebytes. Thanks for that tip though...

I did not go into Windows Defender to exclude the directory. That would have been my next move if this had not works.

Thanks again

11-02-2025, 03:02 AM	#1
Frantishek Junior Member Posts: 1 Karma: 10 Join Date: Nov 2025 Device: ONYX BOOX Note MAX	The program does not launch the interface. Unexpectedly, after restarting the computer (Windows 10) and with no device connected, the program stopped launching. The interface initialization window appears. In Task Manager, there is a running process called - calibre worker process. The previous session of the program was closed correctly by clicking Exit. What has been done to try to fix this (the hanging process is terminated manually): 1. Reinstalled the latest portable version of the program. 2. Moved the portable program folder to the root directory of the disk. Neither helped. What should I do next? (It’s very important not to lose the settings — a lot has been customized in the interface and many plugins have been installed) There were many plugins installed, but the program worked fine with them for more than ten days and launched successfully after each closing. Possible cause: around the same time, I configured another program and changed the Python environment in the system (in case that might be related).

11-10-2025, 03:17 PM	#3
tnavarra Junior Member Posts: 3 Karma: 10 Join Date: Nov 2025 Device: Amazon Paperwhite Kindle	Having s similsr problem This problem started about a month ago after a windows update. I tried rolling Calibre back to the 8.13 version. I have rebooted into safe mode and calibre still does not do anything beyond the splash screen. I have checked the task manager and no calibre processes are running Need some help to get this going. Getting to a critical stage. Thanks in advance Ran the Calibre debug command and this is what I get (windows specs are below): calibre 8.14 embedded-python: True Windows-10-10.0.26200-SP0 Windows ('64bit', 'WindowsPE') ('Windows', '10', '10.0.26200') Python 3.11.14 Windows: ('10', '10.0.26200', 'SP0', 'Multiprocessor Free') Interface language: None EXE path: C:\Program Files\Calibre2\calibre-debug.exe Successfully initialized third party plugins: Gather KFX-ZIP (from KFX Input) (2, 26, 2) && DeDRM (10, 0, 3) && Package KFX (from KFX Input) (2, 26, 2) && BookFusion Plugin (0, 8, 1) && FanFicFare (4, 49, 0) && Goodreads (1, 8, 3) && KFX metadata reader (from KFX Input) (2, 26, 2) && From KFX (2, 26, 2) && KFX Input (2, 26, 2) && Set KFX metadata (from KFX Output) (2, 18, 0) && KFX Output (2, 18, 0) QPA platform: windows devicePixelRatio: 1.0 logicalDpi: 96.0 x 96.0 physicalDpi: 102.45378151260503 x 102.35820895522387 ApplicationPaletteChange event ignored Using calibre Qt style: True ApplicationPaletteChange event received [0.00] Starting up... [0.00] Showing splash screen... [1.19] splash screen shown [1.19] Initializing db... Windows Version: Edition Windows 11 Pro Version 25H2 Installed on ‎12/‎4/‎2024 OS build 26200.7019 Experience Windows Feature Experience Pack 1000.26100.265.0

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Web Interface	PhAzE	Calibre	5	09-29-2014 02:03 PM
Interface seeming erratic	cat-ears	Amazon Kindle	7	03-09-2011 11:14 AM
K3 Interface questions	nessin	Amazon Kindle	4	10-17-2010 09:15 AM
calibre program launch speed	cybmole	Calibre	44	10-16-2010 11:57 PM
OS X Interface	irulan	Calibre	5	09-13-2008 02:18 PM

11-02-2025, 07:28 AM	#2
kovidgoyal creator of calibre Posts: 45,622 Karma: 28549046 Join Date: Oct 2006 Location: Mumbai, India Device: Various	https://manual.calibre-ebook.com/faq...ing-on-windows

Yesterday, 12:28 AM	#4
kovidgoyal creator of calibre Posts: 45,622 Karma: 28549046 Join Date: Oct 2006 Location: Mumbai, India Device: Various	That debug log indicates something is blocking calibre at the database initialization stage. Typical culprits are security/antivirus programs. Try excluding the calibre library folder from these and or disable them temporarily to debug.

Yesterday, 04:12 AM	#6
DNSB Bibliophagist Posts: 48,345 Karma: 174315444 Join Date: Jul 2010 Location: Vancouver Device: Kobo Sage, Libra Colour, Lenovo M8 FHD, Paperwhite 4, Tolino epos	Have you tried starting Windows in safe mode and then launching calibre? This should eliminate a lot of the programs that could be interfering with calibre.

Yesterday, 02:59 PM	#8
tnavarra Junior Member Posts: 3 Karma: 10 Join Date: Nov 2025 Device: Amazon Paperwhite Kindle	Thanks for your help! I got it fixed. I hade to delete the old DB file and then rebuild the database. It worked. My thinking was that since it was hanging on the open database step, perhaps there is something wring with the database. Moved the old ones to a new directory and the program was able to open with a blank library. Rebuilt the DB and they all 5600+books came back in. Just took a few minutes. After the rebuilding, I then closed the program and then re-opened it. Worked perfect. I had started it in safe-mode before I started uninstalling AVG and Malwarebytes. Thanks for that tip though... I did not go into Windows Defender to exclude the directory. That would have been my next move if this had not works. Thanks again