Merge pull request #53482 from abshamsft/patch-19

Adding limitation on redirection and custom error

Author: ktoliver

articles/application-gateway/rewrite-http-headers.md

@@ -5,7 +5,7 @@ services: application-gateway
 author: vhorne
 ms.service: application-gateway
 ms.topic: article
-ms.date: 08/08/2019
+ms.date: 04/27/2020
 ms.author: absha
 ---
 
@@ -153,6 +153,8 @@ You can evaluate an HTTP request or response header for the presence of a header
 
 - If a response has more than one header 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 two Set-Cookie headers: one used by the app service, for example: `Set-Cookie: ARRAffinity=ba127f1caf6ac822b2347cc18bba0364d699ca1ad44d20e0ec01ea80cda2a735;Path=/;HttpOnly;Domain=sitename.azurewebsites.net` and another for application gateway affinity, for example, `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.
 
+- Rewrites are not supported when the application gateway is configured to redirect the requests or to show a custom error page.
+
 - Rewriting the Connection, Upgrade, and Host headers isn't currently supported.
 
 - Header names can contain any alphanumeric characters and specific symbols as defined in [RFC 7230](https://tools.ietf.org/html/rfc7230#page-27). We don't currently support the underscore (\_) special character in Header names.