This is also happening for me now as well – help! This is the second problem I’ve run into this morning with this plugin that used to work fine…
Contacting my hosting provider and asking them to update my mod security rules solved this issue for me.
This didn’t work for me either, and I am getting a similar error when I try to send a test email (or do anything): https://gyazo.com/5e21645774ab1b181e296480098aabfc
I also get the same error: https://gyazo.com/5e21645774ab1b181e296480098aabfc
I have disabled mod security in my htaccess file and there is still no change.
Edit: Contacting my hosting provider and asking them to update my mod security rules solved this issue for me.
