Error started when sending emails

hello i have a pro plan account and iv`e sent many emails
suddenly the actions began to return error when i try to send emails

its a simple email action:
to - user email
body - template (didn’t work with simple text also)

what can i do to check what is the error and fix it please?

What error does it show you on the screen? Or does it not show anything at all?

It just says “error”…

Just says error