Build Status update API error in URL

[Tom Klaver]

Status update API returns:

{"type": "error", "error": {"fields": {"url": ["Enter a valid URL."]}, "message": "Bad request"}}

What requirements are there for the URL? I have a Jenkins endpoint on port 8080, is that a problem?

[Tom Klaver]

After experimenting a little, it turns out the service not accepting an underscore in the URLs domain name (i had something like `test_server.mydomain.com`.