ModSecurity OWASP blocking GTMetrix

If you are using OWASP rules v. 3.3.4 you can experience problem with GTmetrix service. All requests will serve 403 error. It is interesting becouse probably GTmetrix sends forbidden header. GTmetrix is blocked by 3 rules: 920450 - request protocol enforcement 949110 - request blocking evaluation 980130 - response corelation You can disable these rules or add GTmetrix to whitelist (if you need GTmetrix): cPanel has tutorial for whitelisting: