[jeffdonnelly]

Last Update:
okay, using a micro SD card from Samsung, an EVO Plus U3, 256Gb... a very fast card.

It seems that Calibre doesn't like the fact (it throws a comm error after reading the device after it's recognized and reads the P78 Pro and uSD card) that the Meebook P78 Pro writes a mirrored folder structure from the P78 Pro device to the external uSD card. The issue seems, specifically, to be the Android directory it writes to the uSD card.

...and P78 Pro won't let you delete the Android directory from the uSD card without removing it from the P78 Pro, so used a card reader on my PC to delete it, subsequently reinstalling it in the P79 Pro.

However, after reinserting the uSD card into the P78 Pro and rebooting it, the P78 Pro folder structure from the P78 Pro device is again placed onto the external uSD card... including the problematic Android folder (which is un-delete-able while in the P78 Pro).

Then decided to just eject the card while the P78 Pro still on, delete the Android folder from the uSD card via card reader/PC, and hot swap re-install the uSD card in the still running P78 Pro... whichi does NOT re-mirror the folder structure of the P78 Pro and Android folder. Calibre worked fine then...

BUT...

The next issue was, that the P78 Pro has 2 file manager "apps" that are either the standard for Android 11 system (i don't know the answer to that), or specific to the P78 Pro Android tablet e-reader. The apps are called, respectively, "Files"... and "File Manager".

Turns out even with Android folder deleted from uSD card on the PC and hot-swapped back into the P78 Pro with no Android folder present, if you subsequently run the "File Manager" app, the P78 Pro again re-mirrors the folder structure with the Android folder to the uSD card.

BUT - if you run the "FILES" app, it does NOT re-mirror the folder structure with the Android folder - but you have to ensure that the P78 Pro doesn't shut down for power saving, because upon rebooting from cold start, folder structure is mirrored to uSD card again.

Subsequently, i realized that even tho the system won't let you delete the Android folder on the uSD card, it WILL, for some reason allow you to RENAME it, and THEN it WILL let you delete the RENAMED Android folder while the uSD card it mounted in the running P78 Pro.....

I only wish i tried that earlier.... but, once i figure that out, before i connect the USB cable to the PC and Calibre, i ensure that either the Android folder ISN'T present on the uSD card - or if it is - I rename Android folder and then delete it.

THEN, Calibre works with out a hitch, with NO comm errors!