"Could not update option 'smtp_mailer_options" infinite loop restarting

[p44]

Dear All,

I disabled smtp_mailer plugin because is not compatible with DIVI theme contact form feature. I enabled the old one plugin wp mail smtp.

When I restart Wordpress istance I get this error:

Error: Could not update option 'smtp_mailer_options'.

And again, infinite loop, app does not restart.

Can you help me?