KB-1126 How to display detailed error messages in IIS

When configuring a distributed environment with an IIS web server, it may be necessary for detailed error messages to be displayed when the error is encountered by component on a separate host machine. Setting this up is typically done for lower environments, like development or test, or when troubleshooting other issues since the detailed messages are more useful than the default HTTP error codes output by IIS.

To enable this feature, perform the following:

  1. Open the IIS console on the wbe server machine.
  2. Double-click the Error Pages option:
  3. Select the Edit Feature Settings... option:
  4. Change the default setting from the third option, Detailed errors for local requests and custom error pages for remote requests to the second option, Detailed errors:

Default setting:

Detailed setting:

This change will allow remote requests to display detailed errors rather than custom error pages.

Note: If the above steps do not solve the issue, perform the following:

  1. Edit web.config located in the <IIS_DOCUMENT_ROOT> directory.

  2. Find the <system.webServer> element and add or replace (if it exists) the following line:

    <httpErrors errorMode="Detailed"></httpErrors>

    With the following line

    <httpErrors existingResponse="PassThrough" errorMode="Detailed"></httpErrors>
  3. Restart the web server.

Affected Versions

This article applies to all versions of on-premise installations of Appian using Internet Information Services 7.x and later as a web server.

Last Reviewed: February 2017