I cannot start Calibre 9.

AnnieQuinn · 01-30-2026, 09:05 PM

After updating to the new version, I couldn't open the software.

And again, I ran the installer and clicked repair. I've always been able to fix it this way with previous updates.

But this time it didn't work.

Would uninstalling and reinstalling solve the problem?

And what do I need to back up to avoid losing my old settings?

Thank you and I look forward to your help.

BetterRed · 01-30-2026, 09:16 PM

Quote:

Originally Posted by AnnieQuinn

After updating to the new version, I couldn't open the software.

And again, I ran the installer and clicked repair. I've always been able to fix it this way with previous updates.

But this time it didn't work.

Would uninstalling and reinstalling solve the problem?

Maybe, more likely not.

Quote:

Originally Posted by AnnieQuinn

And what do I need to back up to avoid losing my old settings?

Uninstall will not touch your preference settings or libraries.

BR

AnnieQuinn · 01-30-2026, 09:22 PM

Quote:

Originally Posted by BetterRed

Maybe, more likely not.

BR

Feeling a bit nervous, I've gotten used to opening Calibre every day, even though there isn't really that much to do in it.

DNSB · 01-30-2026, 09:26 PM

I would also suggest running calibre from a CLI using calibre-debug -g and see what if any error messages are reported during startup. I've attached a truncated example of what I see on a normal startup for calibre using my Intake library.

Spoiler:

Code:

Microsoft Windows [Version 10.0.26200.7705]
(c) Microsoft Corporation. All rights reserved.

C:\Users\<user>>calibre-debug -g
calibre 9.0*  embedded-python: True
Windows-11-10.0.26200-SP0 Windows ('64bit', 'WindowsPE')
('Windows', '11', '10.0.26200')
Python 3.14.2
Windows: ('11', '10.0.26200', 'SP0', 'Multiprocessor Free')
Interface language: None
EXE path: C:\Program Files\Calibre2\calibre-debug.exe
Successfully initialized third party plugins: ACSM Input (0, 1, 0) && LCPL Input (0, 0, 5) && Gather KFX-ZIP (from KFX Input) (2, 28, 0) && DeDRM (10, 0, 15) && AZW6 Image Merge (1, 1, 2) && Package KFX (from KFX Input) (2, 28, 0) && ACSM Input Plugin GUI Extension (0, 1, 0) && Apple Books covers (1, 1, 0) && Backup Configuration Folder (1, 1, 2) && Baen (1, 1, 0) && Barnes & Noble (1, 5, 7) && Count Pages (1, 14, 4) && Diaps Editing Toolbag (0, 5, 0) && EpubCheck (0, 2, 6) && EpubMerge (3, 2, 0) && EpubSplit (3, 12, 0) && FanFicFare (4, 53, 0) && Find Duplicates (1, 10, 9) && Generate Cover (2, 3, 6) && Goodreads (1, 8, 3) && Job Spy (1, 0, 239) && KFX metadata reader (from KFX Input) (2, 28, 0) && From KFX (2, 28, 0) && KFX Input (2, 28, 0) && Set KFX metadata (from KFX Output) (2, 18, 0) && KFX Output (2, 18, 0) && Kindle hi-res covers (0, 5, 1) && KindleUnpack - The Plugin (0, 83, 8) && Kobo Metadata (1, 12, 0) && Kobo Utilities (2, 25, 0) && Modify ePub (1, 8, 8) && Obok DeDRM (10, 0, 9) && Open With (1, 8, 4) && OverDrive Libby (0, 2, 101) && Quality Check (1, 14, 6) && Resize Cover (1, 2, 1) && ScrambleEbook (0, 6, 0) && SmartEject (2, 6, 0) && Smashwords Metadata (1, 0, 2)
QPA platform: windows
devicePixelRatio: 1.0
logicalDpi: 96.0 x 96.0
physicalDpi: 81.55183946488295 x 81.64285714285714
ApplicationPaletteChange event ignored
Using calibre Qt style: True
ApplicationPaletteChange event received
[0.00] Starting up...
[0.00] Showing splash screen...
[1.14] splash screen shown
[1.14] Initializing db...
[1.17] db initialized
[1.17] Constructing main UI...

<much removed to shorten the log segment>

Driver: KoboTouch'
[2.53] main UI initialized...
[2.53] Hiding splash screen
[2.53] splash screen hidden
[2.53] Started up in 3.53 seconds with 17 books

AnnieQuinn · 01-30-2026, 09:27 PM

Quote:

Originally Posted by DNSB

I would also suggest running calibre from a CLI using calibre-debug -g and see what if any error messages are reported during startup. I've attached a truncated example of what I see on a normal startup for calibre using my Intake library.

Spoiler:

Code:

Microsoft Windows [Version 10.0.26200.7705]
(c) Microsoft Corporation. All rights reserved.

C:\Users\<user>>calibre-debug -g
calibre 9.0*  embedded-python: True
Windows-11-10.0.26200-SP0 Windows ('64bit', 'WindowsPE')
('Windows', '11', '10.0.26200')
Python 3.14.2
Windows: ('11', '10.0.26200', 'SP0', 'Multiprocessor Free')
Interface language: None
EXE path: C:\Program Files\Calibre2\calibre-debug.exe
Successfully initialized third party plugins: ACSM Input (0, 1, 0) && LCPL Input (0, 0, 5) && Gather KFX-ZIP (from KFX Input) (2, 28, 0) && DeDRM (10, 0, 15) && AZW6 Image Merge (1, 1, 2) && Package KFX (from KFX Input) (2, 28, 0) && ACSM Input Plugin GUI Extension (0, 1, 0) && Apple Books covers (1, 1, 0) && Backup Configuration Folder (1, 1, 2) && Baen (1, 1, 0) && Barnes & Noble (1, 5, 7) && Count Pages (1, 14, 4) && Diaps Editing Toolbag (0, 5, 0) && EpubCheck (0, 2, 6) && EpubMerge (3, 2, 0) && EpubSplit (3, 12, 0) && FanFicFare (4, 53, 0) && Find Duplicates (1, 10, 9) && Generate Cover (2, 3, 6) && Goodreads (1, 8, 3) && Job Spy (1, 0, 239) && KFX metadata reader (from KFX Input) (2, 28, 0) && From KFX (2, 28, 0) && KFX Input (2, 28, 0) && Set KFX metadata (from KFX Output) (2, 18, 0) && KFX Output (2, 18, 0) && Kindle hi-res covers (0, 5, 1) && KindleUnpack - The Plugin (0, 83, 8) && Kobo Metadata (1, 12, 0) && Kobo Utilities (2, 25, 0) && Modify ePub (1, 8, 8) && Obok DeDRM (10, 0, 9) && Open With (1, 8, 4) && OverDrive Libby (0, 2, 101) && Quality Check (1, 14, 6) && Resize Cover (1, 2, 1) && ScrambleEbook (0, 6, 0) && SmartEject (2, 6, 0) && Smashwords Metadata (1, 0, 2)
QPA platform: windows
devicePixelRatio: 1.0
logicalDpi: 96.0 x 96.0
physicalDpi: 81.55183946488295 x 81.64285714285714
ApplicationPaletteChange event ignored
Using calibre Qt style: True
ApplicationPaletteChange event received
[0.00] Starting up...
[0.00] Showing splash screen...
[1.14] splash screen shown
[1.14] Initializing db...
[1.17] db initialized
[1.17] Constructing main UI...

<much removed to shorten the log segment>

Driver: KoboTouch'
[2.53] main UI initialized...
[2.53] Hiding splash screen
[2.53] splash screen hidden
[2.53] Started up in 3.53 seconds with 17 books

Thank you, I'll give it a try.

AnnieQuinn · 01-30-2026, 10:27 PM

Uninstalling and reinstalling solved the problem. Thank you for your help.

ownedbycats · 02-01-2026, 11:20 AM

Quote:

Originally Posted by BetterRed

Uninstall will not touch your preference settings or libraries.

Just be careful not to use any third-party uninstallers that do cleanup afterwards. They've been known to nuke users libraries.

01-30-2026, 09:05 PM	#1
AnnieQuinn Zealot Posts: 103 Karma: 216 Join Date: Jan 2024 Location: Vietnam Device: PC, Kindle ppw5, Boox Go 6	I cannot start Calibre 9. After updating to the new version, I couldn't open the software. And again, I ran the installer and clicked repair. I've always been able to fix it this way with previous updates. But this time it didn't work. Would uninstalling and reinstalling solve the problem? And what do I need to back up to avoid losing my old settings? Thank you and I look forward to your help.

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01-30-2026, 10:27 PM	#6
AnnieQuinn Zealot Posts: 103 Karma: 216 Join Date: Jan 2024 Location: Vietnam Device: PC, Kindle ppw5, Boox Go 6	Uninstalling and reinstalling solved the problem. Thank you for your help.