After loading books onto Android Bigme, reconnecting device to calibre causes crash

[Overquoted]

I have a new Bigme B6 Color that runs Android. I can connect it to calibre and transfer books over just fine once. If I then disconnect it and reconnect it, calibre throws errors and the device crashes. If I attempt to write to the device from within Windows explorer, the device crashes but will otherwise stay connected (simply navigating files does not cause the crash).

This behavior does not go away after deleting driveinfo and metadata files. It only goes away upon deleting the entire folder the books were sent to. Deleting the folder and leaving the driveinfo and metadata files, the device connects to calibre fine. So it is something specific to the folders calibre is creating for me on the device, or the files being sent over. I assume?

I would argue this is very likely a bug with the Bigme OS, but they are not well known for fixing bugs so I'm hoping to identify the exact cause just so I can work around it.

calibre, version 9.18.0
ERROR: Unhandled exception: <b>WPDError</b>:C:\r\src\src\calibre\devices\mtp\windows\conten t_enumeration.cpp:528:Failed to EnumObjects() of folder from device:[hr=0x802a0002 wCode=0 name=E_WPD_DEVICE_NOT_OPEN] Shutdown was already called on this object or the object that owns it.: o1B

calibre 9.18 embedded-python: True
Windows-11-10.0.26200-SP0 Windows ('64bit', 'WindowsPE')
('Windows', '11', '10.0.26200')
Python 3.14.10
Windows: ('11', '10.0.26200', 'SP0', 'Multiprocessor Free')
Interface language: None
EXE path: C:\Program Files\Calibre2\calibre.exe
Successfully initialized third party plugins: Gather KFX-ZIP (from KFX Input) (2, 34, 2) && DeDRM (10, 0, 9) && Package KFX (from KFX Input) (2, 34, 2) && Find Duplicates (1, 10, 11) && Goodreads (1, 10, 0) && KFX metadata reader (from KFX Input) (2, 34, 2) && From KFX (2, 34, 2) && KFX Input (2, 34, 2) && KOReader Sync (0, 8, 2) && Kindle hi-res covers (0, 5, 1) && Metadata Sources Preview (1, 0, 2) && Modify ePub (1, 8, 11) && Romance.io (1, 4, 1) && ePub Extended Metadata {Reader} (0, 14, 9) && ePub Extended Metadata {Writer} (0, 14, 9) && ePub Extended Metadata (0, 14, 9)
wpd.WPDError: C:\r\src\src\calibre\devices\mtp\windows\content_e numeration.cpp:528:Failed to EnumObjects() of folder from device:[hr=0x802a0002 wCode=0 name=E_WPD_DEVICE_NOT_OPEN] Shutdown was already called on this object or the object that owns it.: o1B

calibre, version 9.18.0
ERROR: Error: Error communicating with device

C:\r\src\src\calibre\devices\mtp\windows\content_e numeration.cpp:976:Cannot delete object:[hr=0x802a0002 wCode=0 name=E_WPD_DEVICE_NOT_OPEN] Shutdown was already called on this object or the object that owns it.

Traceback (most recent call last):
File "calibre\gui2\device.py", line 112, in run
File "calibre\gui2\device.py", line 606, in _books
File "calibre\devices\mtp\driver.py", line 342, in books
File "calibre\devices\mtp\driver.py", line 312, in get_driveinfo
File "calibre\devices\mtp\driver.py", line 301, in _update_drive_info
File "calibre\devices\mtp\driver.py", line 270, in put_calibre_file
File "calibre\devices\mtp\windows\driver.py", line 43, in check_thread
File "calibre\devices\mtp\windows\driver.py", line 533, in put_file
File "calibre\devices\mtp\windows\driver.py", line 43, in check_thread
File "calibre\devices\mtp\windows\driver.py", line 512, in delete_file_or_folder
wpd.WPDError: C:\r\src\src\calibre\devices\mtp\windows\content_e numeration.cpp:976:Cannot delete object:[hr=0x802a0002 wCode=0 name=E_WPD_DEVICE_NOT_OPEN] Shutdown was already called on this object or the object that owns it.

Edit: I initially thought it may have to do with an SD card, but the issue occurs whether the books are transferred to the internet storage or external card and occurs when the SD card is removed from the device entirely.

[kovidgoyal]

This is a bug in the Bigme firmware. The fact that writing a file from Windows Explorer also crashes the device proves it: Explorer and calibre talk to the device through the same Windows MTP API (WPD), so when a plain Explorer file copy crashes the device, the device's MTP implementation is broken. The errors calibre shows (E_WPD_DEVICE_NOT_OPEN) just mean the device's MTP service has already died and Windows has closed the connection.

When calibre connects to an MTP device, it does very little: it lists the folders on the device and then replaces driveinfo.calibre (deleting the old one and uploading a new one). Those are the most basic MTP operations there are. Your two tracebacks are the device dying during the folder listing and during that delete. The books calibre sends are ordinary files in ordinary folders, so no device should crash just because they exist.

As for finding what triggers it, in my experience Android MTP crashes like this usually come from the device's media index (MediaStore) getting out of sync with the files actually on disk. Some things to try:

1) After the first transfer, reboot the device before reconnecting it. If that fixes things, the cause is the stale media index.

2) Use a file manager on the device to look in the books folder for files calibre did not put there, such as cover caches or .sdr folders created by the reader app or KOReader. Files created on the device are a common cause of this kind of crash.

3) Bisect: move half the books out of the folder on the device, reconnect, and repeat until you find out whether one particular book or folder is the cause.

4) Remove the subfolders from the equation by changing the save template for the device to something flat, such as {title} - {authors}. You can do that by right clicking the device icon in calibre and choosing "Configure this device".

5) If you can't find a workaround, avoid MTP entirely. You can use calibre's wireless device connection with a calibre companion app on the device, or browse calibre's Content server from the device's browser and download books directly.

Whatever you find, please report it to Bigme, since only they can fix the crash itself.