cannot open books in the viewer

james5d · 09-16-2024, 05:11 AM

Trying to use Calibre in a Win10 environment on my computer, but it can't even open it's own user guide which gets added by default, let alone any epub files ( other e-readers have no issue with epub files, so the files are not corrupted ). I've had a previous version of Calibre working in the past ( can't remember which version ). I've installed the current version, removed the program ( using the program wise uninstaller ), then manually removed all user files which seem to be left ( C:/user/appdata ( roaming and local ), and the storage folder, and tried again. I've also tried the portable version ( the previous version number ). No success. Any ideas on what the problem could be ? Thanks

kovidgoyal · 09-16-2024, 06:01 AM

This is caused by incompatibilities between Qt WebEngine (used by the viewer and editor) and the graphics drivers
on your system. Try updating the graphics drivers, if that does not work, you can try disabling hardware acceleration
by setting the environment variable QTWEBENGINE_CHROMIUM_FLAGS="--disable-gpu". If neither of these work then I suggest
downgrading to calibre 7.16 which has an older version of Qt WebEngine for the time being.

james5d · 09-16-2024, 10:16 AM

Graphics card drivers not updated for years, and although can set browser for no hardware acceleration, books still not being displayed. Went with the older portable version you state and that does work, so thanks.

09-16-2024, 05:11 AM	#1
james5d Junior Member Posts: 2 Karma: 10 Join Date: Sep 2024 Device: win10	cannot open books in the viewer Trying to use Calibre in a Win10 environment on my computer, but it can't even open it's own user guide which gets added by default, let alone any epub files ( other e-readers have no issue with epub files, so the files are not corrupted ). I've had a previous version of Calibre working in the past ( can't remember which version ). I've installed the current version, removed the program ( using the program wise uninstaller ), then manually removed all user files which seem to be left ( C:/user/appdata ( roaming and local ), and the storage folder, and tried again. I've also tried the portable version ( the previous version number ). No success. Any ideas on what the problem could be ? Thanks

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09-16-2024, 06:01 AM	#2
kovidgoyal creator of calibre Posts: 44,422 Karma: 24044628 Join Date: Oct 2006 Location: Mumbai, India Device: Various	This is caused by incompatibilities between Qt WebEngine (used by the viewer and editor) and the graphics drivers on your system. Try updating the graphics drivers, if that does not work, you can try disabling hardware acceleration by setting the environment variable QTWEBENGINE_CHROMIUM_FLAGS="--disable-gpu". If neither of these work then I suggest downgrading to calibre 7.16 which has an older version of Qt WebEngine for the time being.

09-16-2024, 10:16 AM	#3
james5d Junior Member Posts: 2 Karma: 10 Join Date: Sep 2024 Device: win10	Graphics card drivers not updated for years, and although can set browser for no hardware acceleration, books still not being displayed. Went with the older portable version you state and that does work, so thanks.

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