Troubleshoot errors running attended or unattended desktop flows

This article provides the mitigation steps for the error codes that may occur during a flow run.

Applies to:   Power Automate
Original KB number:   4555406


When your desktop flow failed to run.


Many errors can occur during a flow run. For more information, see below table.


Every error code not present in this table is not actionable. In that case, contact the customer support.

Error code HTTP status code Run mode Mitigation Steps
InvalidUIFlowsCertificates 401 AttendedUnattended You'll need to install the latest version of desktop flows on your machine. (The security certificate of the desktop flows app has expired.)
WindowsIdentityIncorrect 401 AttendedUnattended Check that you can sign in to the machine using the connection credentials. Below are supported format:
- domain\username -> domain account (domain and AAD)
- username@domain... -> AAD account
- username -> local account
- machine name\username -> local account
- local\username -> local account
- .\username -> local account
NoUnlockedActiveSessionForAttended 400 Attended Check that you are logged in with the correct user and that the session is unlocked on the machine.
SessionCreationError 400 Unattended Check requirements for unattended scenario:
- User the user specified in your connection is a member of the Remote Desktop Users group
- Remote Desktop is enabled on the computer
SessionExistsForTheUserWhenUnattended 400 Unattended Check that you are not logged in with the same user (whatever the state of the session) on the machine.
TooManyActiveSessions 400 Unattended Windows Server only.
You need to log off at least one active session on the machine.
ExistingRecordingSession 400 Local Windows Server only. Check that there is no other user connected to the machine launching a recording or a test playback.
LocalPlaybackOrRecordingOngoing 429 All Check that there is no recording nor test playback ongoing on the machine for the same user session.
UnattendedUnsupportedWithOldConnection 403 Unattended You need to create a new connection on the portal.
RDPIsNotEnabled 400 Unattended You need to enable Remote Desktop on the machine.
UIFlowAlreadyRunning 429 AttendedUnattended A desktop flow is already running on the machine. You need to wait for its completion.
AadLogonFailure 400 Unattended You need to disable Network Level Authentication (NLA) on the machine if you want to use AAD credentials.
Win10AlreadyHasActiveSession 400 Unattended Windows 10 only. You need to log off from the active session on the machine.
UIFlowAgentNotAvailable 400 AttendedUnattended You need to confirm that the service uiflowservice is up and running on your machine. If you have the following error when trying to start uiflowservice, see Desktop flows failure:
Windows could not start the UIFlowService service on Local Computer. Error 1069: The service did not start due to a logon failure
UnableToCallCrlEndpoint 400 AttendedUnattended You need to ensure the revocation list for the certificates can be checked. Ensure that the CRL services are not blocked on the target machine. The services that must be contacted are listed in this article: Limits for automated, scheduled, and instant flows