The reason why you're getting a "406 Not Acceptable" error (either in browser or in error log) is simple: the HTTP request was blocked by our security system.

It doesn't necessarily mean the request was malicious and targeted to exploit system or application vulnerabilities. It could possibly be a false positive, in which case you should just open a support ticket with us and we'll provide more details about the source, reason, and outcome of the supposed-to-be attack.