What to expect from IIS7 custom error module

IIS7 custom error module work in SendResponse stage with priority high (priority high in send response actually means lowest priority) which makes it one of the last modules to run in the pipeline. It produces custom errors only if current statusCode > 400. IIS7 custom error module produces four kinds of custom error responses. These are

1. Custom – This error is produced as per settings in the system.webServer/httpErrors section as seen for the requested URL. For information on how a merged view of section for current URL is produced, go here.
2. Detailed – These errors are produced by custom error module based on information available from IHttpResponse::GetStatus call and some static data. Error response include some internal pipeline information as well and is expected to be viewed by server administrators only.
3. One liners – If custom error module detects that we are about to return a blank response, it sends a one-liner error response in few cases. One line responses are hardcoded for various status codes and are not configurable. These are close to “default” errors of IIS6.
4. Original –If custom error module see a non-blank response text, it assumes that module which changed the status code also produced a useful error message and can return that.

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-Kanwal-