Symptom: You click on a Pro challenge. The page loads, but there is no form, no source code, no output—just a white void. Or you see a generic HTTP 500 - Internal Server Error.
In Burp Proxy → Options → Match and Replace, add: webhackingkr pro fix
Several Pro challenges are designed for old browsers (IE 6, Firefox 3). Modern browsers cause runtime errors. Symptom: You click on a Pro challenge
Often found in "Ping"
