[OpinionatedLurk]

Okay, so last night I tried Safe Mode, Installed Version, with the whole library copied over to the Desktop first. Still no joy:

Spoiler:

calibre, version 7.9.0
ERROR: Failed to repair library: Restoring database failed, click "Show details" to see details

Traceback (most recent call last):
  File "calibre\db\restore.py", line 329, in replace_db
PermissionError: [WinError 32] The process cannot access the file because it is being used by another process: 'C:\\Users\\User\\Desktop\\AO3\\metadata.db' -> 'C:\\Users\\User\\Desktop\\AO3\\metadata_pre_restore.db'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "calibre\db\restore.py", line 160, in run
  File "calibre\db\restore.py", line 334, in replace_db
PermissionError: [WinError 32] The process cannot access the file because it is being used by another process: 'C:\\Users\\User\\Desktop\\AO3\\metadata.db'


-------------
Failed to restore: tamedbanshee/if crazy equals genius (then I'm a (113793)
Traceback (most recent call last):
  File "calibre\db\restore.py", line 306, in restore_books
  File "calibre\db\cache.py", line 86, in call_func_with_lock
  File "calibre\db\cache.py", line 2924, in restore_book
  File "calibre\db\cache.py", line 2145, in create_book_entry
  File "calibre\db\backend.py", line 1147, in execute
  File "C:\t\t\apsw-42s16m2x\src\cursor.c", line 240, in resetcursor
apsw.ConstraintError: ConstraintError: UNIQUE constraint failed: books.id


-------------
Failed to restore: tamedbanshee/crack of the whip (blood in the cu (113800)
Traceback (most recent call last):
  File "calibre\db\restore.py", line 306, in restore_books
  File "calibre\db\cache.py", line 86, in call_func_with_lock
  File "calibre\db\cache.py", line 2924, in restore_book
  File "calibre\db\cache.py", line 2145, in create_book_entry
  File "calibre\db\backend.py", line 1147, in execute
  File "C:\t\t\apsw-42s16m2x\src\cursor.c", line 240, in resetcursor
apsw.ConstraintError: ConstraintError: UNIQUE constraint failed: books.id


-------------
Failed to restore: shirohebi/Hostile Land (131450)
Traceback (most recent call last):
  File "calibre\db\restore.py", line 306, in restore_books
  File "calibre\db\cache.py", line 86, in call_func_with_lock
  File "calibre\db\cache.py", line 2924, in restore_book
  File "calibre\db\cache.py", line 2145, in create_book_entry
  File "calibre\db\backend.py", line 1147, in execute
  File "C:\t\t\apsw-42s16m2x\src\cursor.c", line 240, in resetcursor
apsw.ConstraintError: ConstraintError: UNIQUE constraint failed: books.id


-------------
Failed to restore: CatChan/Sakurama - I _ Childhood (133710)
Traceback (most recent call last):
  File "calibre\db\restore.py", line 306, in restore_books
  File "calibre\db\cache.py", line 86, in call_func_with_lock
  File "calibre\db\cache.py", line 2924, in restore_book
  File "calibre\db\cache.py", line 2145, in create_book_entry
  File "calibre\db\backend.py", line 1147, in execute
  File "C:\t\t\apsw-42s16m2x\src\cursor.c", line 240, in resetcursor
apsw.ConstraintError: ConstraintError: UNIQUE constraint failed: books.id


-------------
Failed to restore: Nikkia/Call it a Senju Sandwich (134846)
Traceback (most recent call last):
  File "calibre\db\restore.py", line 306, in restore_books
  File "calibre\db\cache.py", line 86, in call_func_with_lock
  File "calibre\db\cache.py", line 2924, in restore_book
  File "calibre\db\cache.py", line 2145, in create_book_entry
  File "calibre\db\backend.py", line 1147, in execute
  File "C:\t\t\apsw-42s16m2x\src\cursor.c", line 240, in resetcursor
apsw.ConstraintError: ConstraintError: UNIQUE constraint failed: books.id

(For the record, my (16TB) external drive is wall wort powered (can't get USB powered external drives larger than 5TB) and was plugged directly into the laptop with no hub and no other items plugged into the USB ports.)

I've never used command line with Calibre. I know how to go to Start and find the Command Prompt. Can I just copy/paste from what you have here (except editing the library path) or do I need to navigate to a specific place first? Is it going to be an issue that the new installed version of Calibre doesn't already know this library? Telling it to add library was enough to get it to come up with the "do you want to repair" option, but as mentioned, I've never used CLI with Calibre. Should I use the portable version on the external drive instead?