When loading a user profile on any site meta, e.g. meta.sf, meta.su, or meta.so, a 500 Internal Server Error is returned.
(This image was submitted to me by a site user.)
This is only happening on meta sites, but it is all over the network.
An attempt at fixing an issue with reputation graphs has not taken into account that meta sites don't have reputation.
Sorry about that!
I can take credit for breaking it, but not for fixing it - thanks Nick Craver!