Special:WhatLinksHere on Commons occasionally gives Database errors. For example:
Database error A database query error has occurred. This may indicate a bug in the software. Function: SpecialWhatLinksHere::showIndirectLinks Error: 0
Antoine "hashar" Musso checked on that and wrote:
"The first URL worked for me, the second throws a database error.
Thu Jan 30 14:11:19 UTC 2014 /* query */ Thu Jan 30 14:19:33 UTC 2014 /* query */ Connection lost and reconnected after 59.754s".
This might be related to the fact that both pages within last month or two went through changes that affects update links tables on millions of pages, and those link tables are slow to update, resulting in a state when results of Special:WhatLinksHere do not match the actual linking dependencies.