Suddenly I can't add books to Calibre

[Raver]

I know this problem has been discussed here many times but I didn't find any solution by checking old threads.
I am running calibre on win 11 since years without any issue, suddenly today it won't let me add any new book, it don't let me choose even the source file as it is in not-responding mode for some time before giving the error message. I just updated Calibre but the error is still there.
I have Norton 360 (but I have it since months without problems and calibre is on its white list), just to be sure I disabled it but nothing changes. I tried to disable also DrDrm plugin with no success. I don't have any windows firewall or defender active, no Onedrive active.
This is the error message that I get, I hope someone can give me an hint.
Thanks
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calibre, version 7.5.1
ERROR: Unhandled exception: <b>Exception</b>:File dialog failed (return code 3489660927):

calibre 7.5.1 embedded-python: True
Windows-10-10.0.22631-SP0 Windows ('64bit', 'WindowsPE')
('Windows', '10', '10.0.22631')
Python 3.11.5
Windows: ('10', '10.0.22631', 'SP0', 'Multiprocessor Free')
Interface language: None
EXE path: C:\Program Files\Calibre2\calibre.exe
Successfully initialized third party plugins: DeDRM (10, 0, 3) && Manage Series (1, 5, 2)
Traceback (most recent call last):
File "calibre\gui2\actions\add.py", line 564, in add_books
File "calibre\gui2\__init__.py", line 945, in choose_files_and_remember_all_files
File "calibre\gui2\win_file_dialogs.py", line 268, in choose_files
File "calibre\gui2\win_file_dialogs.py", line 209, in run_file_dialog
Exception: File dialog failed (return code 3489660927):

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[BetterRed]

What happens if you run calibre in Windows Safe mode?

BR

[Raver]

Originally Posted by BetterRed

What happens if you run calibre in Windows Safe mode?

BR

I didn't try before, I tried right now, in safe mode it works ok, I can add books

[Raver]

In normal mode it says "calibre-file-dialog.exe not responding"

[BetterRed]

Do you run a 3rd party file manager, such as XYplorer, Directory Opus, or any third party shell extensions - they often interfere with file operations.

Try setting the CALIBRE_NO_NATIVE_FILEDIALOGS Environment variable to 1.

If that works, its up to you to find the 'culprit', or leave the EnvVar set.

BR

[Raver]

Thanks. I also tried to copy calibre library folder in a different location with a different name but nothing changed.
So I put it again in the original place with the original name and now it seems to work correctly again allowing me to add books. Frankly I don't know how to explain this change.
Let's hope it continues to work.
Thank you again anyway

[JSWolf]

Originally Posted by Raver

In normal mode it says "calibre-file-dialog.exe not responding"

What software do you run when you boot your computer? What add-ins? What AV? You should stop everything and add them back in one-by-one rebooting in between until you find what software needs to be removed.

[Jaws]

Raver, it's also worth checking to see if your computer has automatically updated any device drivers recently. I recently had an issue when USB drivers were updated and it stopped a different Python-based application from running. You should also double-check your Windows Update history — fully expand everything (especially the drivers section) and make sure there's nothing saying "failed" in there. If there is, attempt to reinstall, and then reboot even if it doesn't say a reboot is required.

Failed Windows Updates are a major cause of "my non-Microsoft application just stopped working!" errors. A reboot alone won't fix it, nor (usually) will just fixing an environment variable; if an update has failed, that creates cascades in the Registry. Rather, it creates avalanches in the Registry.

It could be something else, too, but this is worth ruling out.