HTTP Compression – reason codes in etw traces
In one of my earlier posts, I discussed one of the reasons for compression failure and how we identified it using ETW traces and resolved it. Below are the list of other reason codes for your reference.
| NO_ACCEPT_ENCODING | The HTTP request did not contain the Accept-Encoding header |
| COMPRESSION_DISABLED | No permissions for the IIS_WPG group or application pool identity on w3svc/filters/compression node in the IIS metabase file. |
| NO_COMPRESSION_10 | The request is HTTP 1.0 and the IIS metabase key HcNoCompressionForHttp10 value = TRUE |
| NO_COMPRESSION_PROXY | HTTP request contains a Via header which means the request is relayed via a proxy server AND the IIS metabase setting – HcNoCompressionForProxies has a value of TRUE |
| NO_MATCHING_SCHEME | IIS could not find a matching configuration entry for the file extension of the requested web page. This typically means the extension was not added to HcFileExtensions or HcScriptFileExtensions list in IIS metabase. |
| UNKNOWN_ERROR | Unknown reason. |
| NO_COMPRESSION_RANGE | HTTP request contains a Range header and the IIS metabase setting – HcNoCompressionForRange is set to TRUE. |
| FILE_TOO_SMALL | The file size is too small to be compressed. |
| FILE_ENCRYPTED | The requested file is encrypted |
| COMPRESS_FILE_NOT_FOUND | The compressed file was removed since it was compressed. This may also happen on the first request. |
| COMPRESS_FILE_STALE | The compressed file has changed since it was compressed. It may be due to the symptoms described in Microsoft Knowledge Base article: 817442 |
For additional information, refer to this blog post from IIS support team.