Added new Error for unattended desktop flow troubleshooting

Author: iopanag

support/power-platform/power-automate/desktop-flows/troubleshoot-errors-running-attended-or-unattended-desktop-flows.md

@@ -67,3 +67,4 @@ _Original KB number:_   4555406
 |LogonTypeNotGranted|400|Unattended|For more information, see [troubleshooting documentation for logon type not granted](logon-type-has-not-been-granted.md).|
 |UnallowedTenantForConnectWithSignIn|403|Attended|This error occurs when using a [connect with sign-in](/power-automate/desktop-flows/desktop-flow-connections#connect-with-sign-in-for-attended-runs) connection on an Active Directory (AD) domain-joined machine without adding your tenant to the allowlist. </br> For more information, see ["UnallowedTenantForConnectWithSignIn" error in a Power Automate desktop flow](troubleshoot-unallowed-tenant-for-connect-with-sign-in.md).|
 |MachineNotFound|404|Attended</br>Unattended|This error can occur when the machine is unregistered during a run or if the Dataverse organization has been migrated to a different region. Verify that:</br>- Your machine is still registered by [viewing its status](/power-automate/desktop-flows/manage-machines#view-list-of-machines) in the machine runtime application or the Power Automate portal.</br>- Your [desktop flow connection](/power-automate/desktop-flows/desktop-flow-connections) isn't broken in the Power Automate portal.</br>- [Scripting actions](/power-automate/desktop-flows/actions-reference/scripting) in your flow don't register your machine while the flow is running.|
+|NoSessionFoundForPasswordless|400|Unattended|An opened session on the machine is required to run the desktop flow in attended mode. You can also use unattended mode instead using a Power Automate Process license.|