How about Bugzilla?

[Michael Schwendt]

On Thu, 27 Nov 2008 11:19:27 +0000, Peter Robinson wrote:

> > It has severe database connection problems since yesterday (as confirmed
> > by the server-side error messages). Obviously, users who encounter such
> > problems don't sit and wait and retry forever.
> 
> I get those error messages on quite a regular basis. I seem to
> remember they're server 500 error messages with a note about the DB is
> unavailable, or too many connections or something. It eventually comes
> back but it is quite painful.

Yes, proxy errors (failing to connect to remote server) and MySQL bugzilla
db connection limit reached.