Discovered this bug: I've added this module, and added the biblio fields, which works fine. However, I needed to update the index to add another field (normal taxonomy) and I got "The website encountered an unexpected error. Please try again later." - Nothing in the error log.

Disabling this module, enble the extra field, and enabling this module again solved it. So in other words: cannot add more fields to an index after Biblio Search API is enabled. Tried with Drupal 7.31, Search API 1.9, Facet API 1.3