Hello, I was trying to today to test the (User Name Match Regular Expression) option on XF. My forum is an Arabic one so I was trying to add a regex expression to allow the registration with Arabic letters only, I used the following: ^[\u0621-\u064A]+$ Ref: https://en.wikipedia.org/wiki/Arabic_script_in_Unicode I trying to register after applying the above expression but I got an error: (A server error occurred. Please try again later.) Is the Unicode expressions not supported by XF1.5.x or there is an error in my code. Appreciate you help guys.