Duplicate headers seen in HTTP response despite the modify or remove headers behavior is applied in delivery configuration.
Sitecore error “Server cannot modify cookies after HTTP headers have been sent.” - Sitecore Community
![wffm - Sitecore error "Server cannot modify cookies after HTTP headers have been sent." - Sitecore Stack Exchange wffm - Sitecore error "Server cannot modify cookies after HTTP headers have been sent." - Sitecore Stack Exchange](https://i.stack.imgur.com/5qG89.png)
wffm - Sitecore error "Server cannot modify cookies after HTTP headers have been sent." - Sitecore Stack Exchange
Sitecore error “Server cannot modify cookies after HTTP headers have been sent.” - Sitecore Community
Sitecore error “Server cannot modify cookies after HTTP headers have been sent.” - Sitecore Community
Server cannot modify cookies after HTTP headers have been sent" error with SignalR · Issue #6 · Sustainsys/owin-cookie-saver · GitHub
![server cannot modify cookies after http headers have been sent – Sitecore Genie – Himanshu Agarwal's blog server cannot modify cookies after http headers have been sent – Sitecore Genie – Himanshu Agarwal's blog](https://sitecoregenie.files.wordpress.com/2020/04/image009.jpg)