Calibre Won't Launch - Splash Screen Only

[nedd]

Hi!

I've gone through all the solutions I've found so far (uninstall/reinstall, repair, windows start mode, cascading windows, emptying temp folder, deleting metadata files) and no luck: starting Calibre gives a splash screen, then just the icon on the task bar (hovering over which previews a black rectangle).

Did not try removing the DeDRM plug-in, as can't open the program to do so.

Waiting - even for hours/overnight - changes nothing.

Debug results gave this:

C:\Users\name>calibre-debug -g
calibre 7.9 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\Calibre24\calibre-debug.exe
Successfully initialized third party plugins: DeDRM (7, 1, 0) && EpubSplit (3, 6, 0) && Kindle hi-res covers (0, 5, 0) && KindleUnpack - The Plugin (0, 83, 1) && Obok DeDRM (6, 7, 0)
qt.qpa.screen: "Unable to open monitor interface to \\\\.\\DISPLAY1:" "The operation completed successfully."
QPA platform: windows
devicePixelRatio: 1.0
logicalDpi: 96.0 x 96.0
physicalDpi: 96.0 x 95.9160839160839
ApplicationPaletteChange event ignored
Using calibre Qt style: True

Any ideas are very welcome - thank you!

[kovidgoyal]

See the line

qt.qpa.screen: "Unable to open monitor interface to \\\\.\\DISPLAY1:" "The operation completed successfully."

This indicates Qt is unable to query the OS for your monitor. That is likely the cause. I'm not a windows user so I dont have any ideas for what might the underlying issue be, but in general, my suggestions are: update the drivers on your machine, try plugging the monitor into a different port in case it is an external monitor, run a registry cleaner, reboot in safe mode.

[theducks]

DISPLAY1: Is this a pseudo device (or spyware)

CON:, LPT1:, NUL: ...
These I know