Comment 7 for bug 1758548

Hi,

First, thank you very much for your help.
As for the special characters in French (é, è, à, ç, ë, ê ...) do not seem to be the cause of the problem. Or did not I notice?

On the other hand, it is the change in the case of characters that is decisive:
Indeed, I did a test on a book saved in epub and ORIGINAL_epub formats.
Then, I copied this same title in the same library in epub format as well.

So, in duplicate. When opening in the editor for reading, no problem.

Then, I change the name of the author (First Name Last Name > First Name Last NAME) on a copy and I save.
Well, the cover has disappeared, ditto for the book (both copies!?)
Only the opf file remains. If I try to open it, I get the following error:

 calibre, version 3.30.0
ERROR: Unable to open eBook: Failed to read the book, / media / m**** / S***_livres / Library calibre / Claude-Catherine Kiejman / Eleanor Roosevelt _ First lady and rebel (22254) /metadata.opf click "Show details " for more information

Traceback (most recent call last):
  File "site-packages / template / utils / ipc / simple_worker.py", line 289, in main
  File "site-packages / template / ebooks / oeb / iterator / book.py", line 65, in extract_book
  File "site-packages / caliber / customize / conversion.py", line 246, in __call__
  File "site-packages / template / ebooks / conversion / plugins / html_input.py", line 90, in convert
  File "site-packages / template / ebooks / conversion / plumber.py", line 1311, in create_oebbook
  File "site-packages / template / ebooks / oeb / reader.py", line 72, in __call__
  File "site-packages / template / ebooks / oeb / reader.py", line 704, in _all_from_opf
  File "site-packages / caliber / ebooks / oeb / reader.py", line 349, in _spine_from_opf
OEBError: Spine is empty

A priori, the problem originates from the management of lowercase and uppercase by Calibre (Title > TITLE, First name Lastname > Firstname LastNAME).

Have a great day.