- If a response has more than one headers with the same name, then rewriting the value of one of those headers will result in dropping the other headers in the response. This can usually happen with Set-Cookie header since you can have more than one Set-Cookie header in a response. One such scenario is when you are using an app service with an application gateway and have configured cookie-based session affinity on the application gateway. In this case the response will contain 2 Set-Cookie headers: one used by the app service, i.e., `Set-Cookie: ARRAffinity=ba127f1caf6ac822b2347cc18bba0364d699ca1ad44d20e0ec01ea80cda2a735;Path=/;HttpOnly;Domain=sitename.azurewebsites.net` and another for application gateway affinity, i.e., `Set-Cookie: ApplicationGatewayAffinity=c1a2bd51lfd396387f96bl9cc3d2c516; Path=/`. Rewriting one of the Set-Cookie headers in this scenario can result in removing the other Set-Cookie header from the response.