KB-1741 Configuring the Connected System Object for OAuth 2.0 integration fails with "The client MUST NOT use more than one authentication method in each request." pink box error

This issue has been resolved in an Appian hotfix/new Appian version. Please apply the latest hotfix to your Appian installation or upgrade to the latest version of Appian.


When configuring the Connected System Object to use OAuth 2.0, pressing Authorize returns the following pink box error:


When using OAuth with a Connected System in Appian versions 17.4 to 18.2, Appian is using basic authentication but is also sending the 'client_id' and 'client_secret' credentials in the post data of the request against the token endpoint, as well as in the authorization header. This causes authentication against certain systems to fail with the above error.

This issue has been addressed in Appian 18.3.


Upgrade to Appian version 18.3 or higher.

Affected Versions

This article applies to Appian 17.4 to Appian 18.2.

Last Reviewed: October 2018