Hi Luca,

I hope you are well today and thank you for your question.

The error occurs when server allocates less than required maximum execution time to PHP so try increasing maximum execution time by using following solutions and if the solutions don’t help then contact your web host to increase it.

https://codex.wordpress.org/Common_WordPress_Errors#Maximum_execution_time_exceeded

http://www.wpbeginner.com/wp-tutorials/how-to-fix-fatal-error-maximum-execution-time-exceeded-in-wordpress/

https://wordpress.org/plugins/wp-maximum-execution-time-exceeded/

Best regards,
Shufflehound team