i got this error trying to log in for my first time

Haven’t seen that error - did you get through eventually?

all first times are eventually 🙂

I didn’t try again and didn’t try to do anything more … but i got the registration email and clojurians zulip is working fine

That's a django error. Worth reporting to the zulip team. They were very proud of having less than ten minutes downtime in 5 years, so they will be keen to know about this!