KB-2367 OAuth 2.0 Client Credentials Grant connected system shows errors despite successful connection

Ryan Good — Tue, 27 Jan 2026 05:41:04 GMT

Current Revision posted to Appian Knowledge Base by Ryan Good on 1/27/2026 5:41:04 AM

Symptoms

When using OAuth 2.0 Client Credentials Grant as a Connected System Object's authentication, the following errors are seen in tomcat-stdOut.log even though the connection is successful:

ERROR com.appiancorp.connectedsystems.http.execution.AppianHttpRequestExecutor - ConnectorRuntimeException [title=Connection failed, Could not authenticate with the connected system or connect to the external system at the specified URL]

ERROR com.appiancorp.connectedsystems.http.execution.AppianHttpRequestExecutorPipeline - Could not authenticate with the connected system (UUID: <UUID>) or connect to the external system at the specified URL (<endpoint>). Check that the credentials in the connected system are correct and test the connection.

There is also a log entry line about OAuth token retrieval:

INFO com.appiancorp.connectedsystems.http.oauth.HttpOAuthTokenRetriever - Error while retrieving token: request_error attempting to pass Authentication in body

Cause

The OAuth 2.0 endpoint is incorrectly configured to expect Client Credentials in the request body.

Appian follows the ITEF RFC 6749 standard for OAuth 2.0 Client Credentials Grant. This standard specifies that including the client credentials in the request body is not recommended.

Appian sends client credentials in the authentication request header (as this is the preferred way by ITEF RFC 6749). If the request with credentials in the header fails, Appian will try again with the credentials in the request body.

Action

Configure the OAuth 2.0 endpoint to expect Client Credentials from Appian in the request header.

Affected Versions

This article applies to all versions of Appian.

Last Reviewed: January 2026

Tags: integration

[New] [DRAFT SUPP-491] KB-XXXX OAuth 2.0 Client Credentials Grant connected system shows retries

Ryan Good — Mon, 19 Jan 2026 05:51:05 GMT

Revision 4 posted to Appian Knowledge Base by Ryan Good on 1/19/2026 5:51:05 AM

Symptoms

When using OAuth 2.0 Client Credentials Grant as a Connected System Object's authentication, the following errors are seen in tomcat-stdOut.log even though the connection is successful:

ERROR com.appiancorp.connectedsystems.http.execution.AppianHttpRequestExecutor - ConnectorRuntimeException [title=Connection failed, Could not authenticate with the connected system or connect to the external system at the specified URL]

ERROR com.appiancorp.connectedsystems.http.execution.AppianHttpRequestExecutorPipeline - Could not authenticate with the connected system (UUID: <UUID>) or connect to the external system at the specified URL (<endpoint>). Check that the credentials in the connected system are correct and test the connection.

There is also a log entry line about OAuth token retrieval:

INFO com.appiancorp.connectedsystems.http.oauth.HttpOAuthTokenRetriever - Error while retrieving token: request_error attempting to pass Authentication in body

Cause

The OAuth 2.0 endpoint is incorrectly configured to expect Client Credentials in the request body.

Appian follows the ITEF RFC 6749 standard for OAuth 2.0 Client Credentials Grant. This standard specifies that including the client credentials in the request body is not recommended.

Action

Configure the OAuth 2.0 endpoint to expect Client Credentials from Appian in the request header.

Affected Versions

This article applies to all versions of Appian.

Last Reviewed: January 2026

Tags: integration

[New] [DRAFT SUPP-491] KB-XXXX OAuth 2.0 Client Credentials Grant connected system shows retries

Maggie Deppe-Walker — Mon, 19 Jan 2026 05:27:17 GMT

Revision 3 posted to Appian Knowledge Base by Maggie Deppe-Walker on 1/19/2026 5:27:17 AM

Symptoms

When using OAuth 2.0 Client Credentials Grant as a Connected System Object's authentication, the following errors are seen in tomcat-stdOut.log even though the connection is successful:

ERROR com.appiancorp.connectedsystems.http.execution.AppianHttpRequestExecutor - ConnectorRuntimeException [title=Connection failed, Could not authenticate with the connected system or connect to the external system at the specified URL]

ERROR com.appiancorp.connectedsystems.http.execution.AppianHttpRequestExecutorPipeline - Could not authenticate with the connected system (UUID: <UUID>) or connect to the external system at the specified URL (<endpoint>). Check that the credentials in the connected system are correct and test the connection.

There is also a log entry line about OAuth token retrieval:

INFO com.appiancorp.connectedsystems.http.oauth.HttpOAuthTokenRetriever - Error while retrieving token: request_error attempting to pass Authentication in body

Cause

The OAuth 2.0 endpoint is incorrectly configured to expect Client Credentials in the request body.

Appian follows the ITEF RFC 6749 standard for OAuth 2.0 Client Credentials grant. This standard specifies that including the client credentials in the request body is not recommended.

Action

Configure the OAuth 2.0 endpoint to expect Client Credentials from Appian in the request header.

Affected Versions

This article applies to all versions of Appian.

Last Reviewed: Month YYYY

Tags: integration

[NEW] KB-XXXX OAuth 2.0 Client Credentials Grant connected system shows retries

Maggie Deppe-Walker — Mon, 19 Jan 2026 05:26:42 GMT

Revision 2 posted to Appian Knowledge Base by Maggie Deppe-Walker on 1/19/2026 5:26:42 AM

Symptoms

When using OAuth 2.0 Client Credentials Grant as a Connected System Object's authentication, the following errors are seen in tomcat-stdOut.log even though the connection is successful:

ERROR com.appiancorp.connectedsystems.http.execution.AppianHttpRequestExecutor - ConnectorRuntimeException [title=Connection failed, Could not authenticate with the connected system or connect to the external system at the specified URL]

ERROR com.appiancorp.connectedsystems.http.execution.AppianHttpRequestExecutorPipeline - Could not authenticate with the connected system (UUID: <UUID>) or connect to the external system at the specified URL (<endpoint>). Check that the credentials in the connected system are correct and test the connection.

There is also a log entry line about OAuth token retrieval:

INFO com.appiancorp.connectedsystems.http.oauth.HttpOAuthTokenRetriever - Error while retrieving token: request_error attempting to pass Authentication in body

Cause

The OAuth 2.0 endpoint is incorrectly configured to expect Client Credentials in the request body.

Appian follows the ITEF RFC 6749 standard for OAuth 2.0 Client Credentials grant. This standard specifies that including the client credentials in the request body is not recommended.

Action

Configure the OAuth 2.0 endpoint to expect Client Credentials from Appian in the request header.

Affected Versions

This article applies to all versions of Appian.

Last Reviewed: Month YYYY

Tags: integration

[NEW] KB-XXXX OAuth debug logs show failure and success

Maggie Deppe-Walker — Mon, 19 Jan 2026 05:13:33 GMT

Revision 1 posted to Appian Knowledge Base by Maggie Deppe-Walker on 1/19/2026 5:13:33 AM

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Affected Versions

This section includes any relevant version information for Appian or other third/party configurations. Some examples of valid affected versions are as follows:

This article applies to all versions of Appian.
This article applies to all self-managed versions of Appian.
This article applies to all versions of Appian Cloud.
This article applies to Appian 7.11 and later.
This article applies to Appian 16.2 and earlier.
This article applies to Appian 7.11 and 16.1.
This article applies to Appian 16.1, 16.2, and 16.3.
This article applies to self-managed Appian 19.3 and earlier.
This article applies to all versions of Appian from Appian 7.10 to Appian 16.2.
This article applies to all versions of Appian using JBoss EAP 6.4.9 as an application server and Internet Explorer 9 as a web browser.

Last Reviewed: Month YYYY