Last night I had a programme running and it errored on the first call to the badges/name endpoint on the API, exact API endpoint call:

https://api.stackexchange.com/2.2/badges/name?order=asc&sort=rank&site=stackoverflow&pagesize=100&page=1

Response:

{"error_id":500,"error_message":"this error has been logged","error_name":"internal_error"}

First occurrence: approximately 00:00UTC+00:00
Most recent occurrence: 06:17UTC+00:00

Update: this is back, has been happening for several days for me now, latest at 00:05UTC+00:00 on 18 January 2017.

Verified with and without application key. Verified from three independent IP addresses (and computers).

API docs recommend posting a question on Stack Apps, so here it is.