In the Fiddler log I see this: 19:13:42:5608 [HTTPWarning] Header folding detected. Not all clients properly handle folded headers. I need to know what session that is from. I have thousands of sessions. If you could just add from session 1234 then I would know. Thanks v5.0.20181.14850 for .NET 4.6.1 Built: Tuesday, March 20, 2018