![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/2018/09/servercookie.png?w=640)
server cannot modify cookies after http headers have been sent – Sitecore Genie – Himanshu Agarwal's blog
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/nmjah.png)
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 wffm - Sitecore error "Server cannot modify cookies after HTTP headers have been sent." - Sitecore Stack Exchange](https://i.stack.imgur.com/5qG89.png)