401 Unauthorized Error - Start Microsoft Teams Chat

[VSimranS]

We are facing an issue while initiating a Microsoft Teams chat from a ServiceNow Incident record using the <b>Start Microsoft Teams Chat</b> UI action.

<h3>Current Behavior &amp; Symptoms</h3>

<ul>
<li>Clicking Start Microsoft Teams Chat results in an <b>HTTP 401 - Unauthorized</b> error.</li>
<li>Error message: <b>"Invalid Access token. Please check your credential alias."</b></li>
<li>The OAuth 2.0 Credential record (Microsoft Teams Chat Single Tenant Credential) shows that an active refresh token is available with a valid expiry date.</li>
<li>The <b>MS_Teams_Chat_Credentials</b> alias and associated connection are active.</li>
<li>The connection URL is <b>https://graph.microsoft.com</b>.</li>
<li>The associated Microsoft Azure credential is active.</li>
</ul>

<h3>Questions</h3>

<ol>
<li>Why does the request return HTTP 401 even though a valid refresh token is available?</li>
<li>Does Start Microsoft Teams Chat use a different OAuth credential or credential alias?</li>
<li>How can we identify which credential alias and access token are being used by MSTeamsChatAjaxProcessor?</li>
<li>Are additional Microsoft Graph API permissions, OAuth scopes, or admin consent required?</li>
<li>Are there any known configuration requirements for using one Microsoft Teams tenant across multiple ServiceNow instances?</li>
</ol>

<p>We have verified that the credential alias and connection exist, but the issue persists.</p>

<p>Any guidance or suggestions would be appreciated.</p>

<p>Thanks in advance!</p>