Mail not sending after updating to latest version



I just (last week) updated to the latest version, and after that, no longer mails are being sent... I double checked and updated the cron jobs, and they are exactly as mailwizz told me that should be, but still doesn't work... after the update I was in a very old mailwizz version, and everything worked absolutely ok.

Please, I need some help....

What could be wrong?
it worked! For some reason sendgrid wasn't working; the apu key ahs changed... I just created an other api key and read the server in mailwizz with the new api key...

hope this is useful to somebody!!