I'm still receiving the cannot update metadata on ebooks and I think part of the problem is if there is no data to fill in the custom column (like if a story has 0 reviews) I receive the error message that the metadata couldn't be updated. However, the other custom columns filled in information.
Here is the message I recieved on the latest story download.
calibre, version 1.3.0
ERROR: Error Updating Metadata: <p>An error has occurred while FFDL was updating calibre's metadata for <a href='http://archiveofourown.org/works/968232'>The Victory of Shadows</a>.</p>The ebook has been updated, but the metadata has not.
Traceback (most recent call last):
File "calibre_plugins.fanfictiondownloader_plugin.ffdl_ plugin", line 1113, in update_books_loop
File "calibre_plugins.fanfictiondownloader_plugin.ffdl_ plugin", line 1512, in update_metadata
File "site-packages\calibre\db\legacy.py", line 646, in set_custom
File "site-packages\calibre\db\cache.py", line 939, in set_field
File "site-packages\calibre\db\write.py", line 509, in set_books
File "site-packages\calibre\db\write.py", line 509, in <dictcomp>
File "site-packages\calibre\db\write.py", line 88, in adapt_number
ValueError: invalid literal for int() with base 10: ''