KB-1093 "HTTP Error 403.14 - Forbidden" error thrown when accessing Appian with IIS as a web server


After starting the application server and IIS, accessing any Appian URL that contains "/suite" will result in the following 403.14-Forbidden error screen:

Accessing the the root domain will successfully load the IIS screen, however.


The probable causes for this error are the following:

  1. The ISAPI module (isapi_redirect.dll) is failing to properly load. This happens when IIS was set up with a specific version of the module, either 32-bit or 64-bit, and was later modified.
  2. Windows Process Activation Service is not enabled.

Note: The error page may suggest to enable directory browsing, this can safely be disregarded.


  1. It is possible that the incorrect ISAPI Redirector DLL is being referenced and the ISAPI module may need to be reconfigured. To reconfigure the ISAPI module, perform the following:
    1. Delete the ISAPI module set up in step 8 of the Set Up IIS documentation.
    2. Once deleted, change the setting ‘Enable 32-Bit Applications’ configured in step 9 of Set Up IIS documentation to ‘False’.
    3. Recreate the ISAPI module from step 12 of the Set Up IIS documentation. If you no longer get an error, this means you were using the 64-bit ISAPI Redirector DLL.
  2. If the error still exists, enable Windows Process Activation Service and all its sub processes in "Turn Windows features on or off".

Affected Versions

This article applies to all versions of Appian using IIS as the web server.

Last Reviewed: January 2021