Problem opening pdfs (from https://z-lib.org/)

calibre, version 5.10.1
ERROR: Errors while adding: Failed to add any books, click "Show details" for more information


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Failed to add the book: Architects of Light Manual.pdf
/home/bronner/Calibre Library/Architects of light hanbook-1 by Ashayana deane.pdf
With error:
Traceback (most recent call last):
File "calibre/gui2/add.py", line 457, in add_book
File "calibre/db/legacy.py", line 334, in create_book_entry
File "calibre/db/cache.py", line 72, in call_func_with_lock
File "calibre/db/cache.py", line 1672, in create_book_entry
File "calibre/db/backend.py", line 920, in execute
apsw.ReadOnlyError: ReadOnlyError: attempt to write a readonly database