Configuring HTTP.sys Error Logging

Applies To: Windows Server 2003, Windows Server 2003 with SP1

To change the configuration of HTTP.sys error logging, you must edit the registry. HTTP.sys reads the configuration only once during startup. If you change the configuration, HTTP.sys can pick up the change only at the next startup. The HTTP.sys error logging configuration is global.

You must have administrative credentials to edit the HTTP.sys configuration in the registry.


Do not edit the registry unless you have no alternative. The registry editor bypasses standard safeguards, allowing settings that can damage your system, or even require you to reinstall Windows. If you must edit the registry, back it up first and see the Windows Server 2003 Resource Kit Registry Reference.

Registry Parameters

Three parameters control HTTP.sys error logging. They are located under the following registry key: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\HTTP\Parameters.

There are three entries that can be set:

  • EnableErrorLogging (DWORD). The default value is TRUE.

  • ErrorLogFileTruncateSize (DWORD). The default value is 1 * 1024 * 1024 bytes. The value cannot be smaller than this, and it must be specified in bytes.

  • ErrorLoggingDir (String). The default value is \systemroot\System32\LogFiles. When specified, this value must be a fully qualified directory string, but you can use \systemroot. For example:


    — or —


Although you can specify the directory, HTTP.sys will create a subdirectory named HTTPERR under the given log directory and put the error log files in this subdirectory. By default, members of the Administrators group and users with a LocalSystem user account have full access to the log files and directories. No other users have access rights.

The log file naming convention for HTTP.sys error logging is Httperr.#, where # is a sequence number. HTTP.sys error log files have a .log extension. For example, Httperr1.log. The error log files are recycled, based on their sizes. The default recycle size for error log files is 1 megabyte (MB). You can configure the value in the registry, but it cannot be smaller than 1 MB.

When the following events occur, HTTP.sys records them in the Windows Event log:

  • HTTP.sys cannot create an error log file.

  • The administrator sets an unacceptable configuration in the registry.

  • There is not enough disk space.

  • There is any other write failure.