error creating deal from a contact

I get this error everytime I am creating a deal from a contact preview ¿any idea what could it be?

Hi @NDiazApache,

Habe you tried disabling all browser extensions and clearing cache and cookies, or another browser or a private tab? This could rule out a browser issue.

Best regards

Hi! Yes, tried the extensions and the clearing cache and cookies.
Just tried in Chrome instead of Firefox and it worked.
Have always worked on firefox, don’t know what happened
Tks for your answer