Successful login through custom domain raises error 500

I have a custom cname for my team and when anybody login the redirection raises a http 500 error.

The pages says:

"This might be useful in debugging the problem:
bb292d5cfcbb414a971a9efab034bcf2$5aa953dc331e55c0a255d5fd3c6e2925"

Clicking on the logo or reloading the page, the homepage is loaded succesfully with the user logged in.

But the behaviour is annoying.