I’ve helped many users who say Fiddler has “fixed” their issue. Unfortunately, this is a bit deceptive. Fiddler is an excellent debugging tool for web apps, but it does not permanently resolve problems. What it does do is act as a proxy with its own connection settings. This allows it to act as a “man in the middle” and even decrypt the traffic to provide better more insight into application behavior.
Just because you can do something doesn’t always mean you should. One such example of this is using large HTTP headers. While the HTTP specification itself doesn’t set boundaries, most web servers have default limits around 8 KB. Other devices in the path such as firewalls/WAFs, proxies, and load balancers also have similar limits. Problem The application testers were receiving a reset error. Their application and web server logs did not show any problems.