Hi,
Okay, thank you for the information.
All right, so if there is nothing in relation in the error log, then those might be bfrom botted/automated requests as they suggested, which have been caught in the firewall but still flagged as “internal server error 500”. There is also a defense try->catch statement around the handler, which will signal an error state when malformed data is sent, so the server doesn’t have to deal with it. However that would be logged in the error log for sure, so I am guessing it is the automated requests.
For now you can safely ignore it in my honest opinion, there is no sign of any serious issue behind it. If it comes back regularly, then let me know. In that case I will have to do an in depth code debugging via (s)FTP to try to re-create the problem.