(Some) iRule 'HTTP::header remove' causes TCL error following 11.6 HF4 upgrade

Hi Greg,

Are you sure that the ONLY change in your F5 configuration was the upgrade from HF3 to HF4?

"Operation not supported" error usually happens if you are trying to modify the headers AFTER another iRule assigned to the same virtual server (or the same iRule but elsewhere in the code) has already responded/closed or redirected this request.

This potentially might explain why you see this issue intermittently - if your iRule redirects some users based on some user-specific criteria (e.g. URL or a cookie) - these users will have their connections reset and TCL error "Operation not supported" logged.

Hope this helps,

Sam