[FaceDeer]

That better error reporting thing might just have raised its first flags. Testing out my new system using the "Created"/"Packaged" date, I went and grabbed 1200 fanfics off of fanfiction.net that were a mixture of ones I had already and new ones. I ran into 12 instances of the error:

calibre, version 1.0.0
ERROR: Error Updating Metadata: <p>An error has occurred while FFDL was updating calibre's metadata for <a href='http://www.fanfiction.net/s/9587231/1/'>The Legend of the Titans</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 1117, in update_books_loop
File "calibre_plugins.fanfictiondownloader_plugin.ffdl_ plugin", line 1535, in update_metadata
KeyError: None

However, inspecting several of the fanfics with errors afterward seemed to show that the metadata in my database had indeed been updated to match what was on the site. So maybe these are false positives?

I tried redownloading the twelve and the errors all popped up again, so this is repeatable for me at least. The fanfics in question are:

http://www.fanfiction.net/s/8220675/1/
http://www.fanfiction.net/s/9125974/1/
http://www.fanfiction.net/s/9497792/1/
http://www.fanfiction.net/s/9499806/1/
http://www.fanfiction.net/s/9515957/1/
http://www.fanfiction.net/s/9545052/1/
http://www.fanfiction.net/s/9572375/1/
http://www.fanfiction.net/s/9587231/1/
http://www.fanfiction.net/s/9617841/1/
http://www.fanfiction.net/s/9622698/1/
http://www.fanfiction.net/s/9627992/1/
http://www.fanfiction.net/s/9636580/1/

Edit: Unfortunately the new error reporting hasn't turned up anything regarding my trouble with FFDL on my laptop, it still just quietly hangs at the "updating calibre with fanfiction stories" step. I figure I'll wait until weekend to try out the next Calibre update, to see if anything gets fixed in that that affects this, and then try the tear-it-all-down-and-rebuild approach.