Error Communicating With Device

[SteveG23]

BetterRed - Thanks for the hint, though actually you pointed me right back to this thread . . . . Now I see I actually first posted it here:
https://www.mobileread.com/forums/sh...d.php?t=338723
No substantive reply yet in either place. (Not that it's been that long, and it may be a mystery.)

[kovidgoyal]

That is an error listing the files in the device storage. This has been known to happen with some
devices when they contain SD cards. If you remove the SD card, you should be fine. You can try reformatting the card
or using a different card as well.
If you arent using an SD card then your remaining options are reset of the device or use a wireless connection as described here: https://manual.calibre-ebook.com/faq...kindle-fire-hd

[SteveG23]

This is very strange. I have been using (and supporting) Calibre for at least eight years, and using it with this phone and this SD card for over a year without any problem. Did a recent update to Calibre cause this?

I went ahead and moved my ebook files to the main memory (using up a substantial part of the available memory!), reformatted the SD card, and with the card still out, Calibre would communicate with it and list the files in main memory. I tried to "Configure this device" to ignore the SD card, but unless the card is inserted, there doesn't seem to be a way to do that; and if I reinsert the card and try to "Configure this device" I get "ThreadingViolation:You cannot use the MTP driver from a thread other than the thread in which startup() was called." Of course I have no idea what that means. The full error:

calibre, version 5.34.0
ERROR: Unhandled exception: <b>ThreadingViolation</b>:You cannot use the MTP driver from a thread other than the thread in which startup() was called

calibre 5.34 [64bit] embedded-python: True is64bit: True
Windows-10-10.0.19041 Windows ('64bit', 'WindowsPE')
('Windows', '10', '10.0.19041')
Python 3.8.5
Windows: ('10', '10.0.19041', '', 'Multiprocessor Free')
Interface language: None
Successfully initialized third party plugins: DeDRM (7, 2, 1) && Kobo Utilities (2, 15, 1) && Overdrive Link (2, 50, 0) && Resize Cover (1, 1, 0) && Overdrive Link* (2, 50, 0)
Traceback (most recent call last):
File "calibre\gui2\device_drivers\mtp_config.py", line 434, in change_ignored_folders
File "calibre\gui2\device_drivers\mtp_folder_browser.py ", line 119, in __init__
File "calibre\devices\mtp\windows\driver.py", line 257, in filesystem_cache
File "calibre\devices\mtp\windows\driver.py", line 35, in check_thread
calibre.devices.mtp.windows.driver.ThreadingViolat ion: You cannot use the MTP driver from a thread other than the thread in which startup() was called

Is there no way to get it to just ignore the card? Are you saying that after all these years, I will have to stop using Calibre? Of course using my smartphone without an SD card is not a reasonable option.

[kovidgoyal]

If you read my actual post, it lists all your options.