Issue saving email template


I just logged in the software to prepare a new newsletter and I get this error.

Screen Shot 2019-05-07 at 10.29.30 AM.png
I haven't done any update to the Mailwizz and I don't know if it is a problem with Mailwizz or the server it is on.
How can I troubleshoot that?

I see I have an update ready on my dashboard:
  • Version 1.7.5 is now available for download. Please update your application!
I have now version 1.7.2.

Wonder if I should update before getting the issue resolves?

Thank you for your help.
You host has enabled mod_security on your account, have them disable it and things will work just fine.
Mod_security triggers when it seems html content, which happens when you save your template.