Error code occurs when running an attended or unattended desktop flow

This article provides the mitigation steps for the error codes that occur when running attended or unattended desktop flows.

Applies to:   Power Automate
Original KB number:   4555406

Note

If the error code that you receive is not listed in the table, contact Power Automate support.

Error code	HTTP status code	Run mode	Mitigation steps
UnsupportedRpaScriptSchemaVersion	400	Attended Unattended	The selected flow was issued by a later version of Power Automate for desktop. You'll need to install the latest version of Power Automate for desktop on your machine.
InvalidUIFlowsCertificates	401	Attended Unattended	You'll need to install the latest version of desktop flows on your machine as the security certificate of the desktop flows app has expired.
WindowsIdentityIncorrect	401	Attended Unattended	Check that you can sign in to the machine using the connection credentials. Below are supported format: - domain\username -> domain account (domain and Microsoft Entra ID) - username@domain... -> Microsoft Entra account - username -> local account - machine name\username -> local account - local\username -> local account - .\username -> local account
NoUnlockedActiveSessionForAttended	400	Attended	Check that you're logged in with the correct user and that the session is unlocked on the machine. For more information about this error code, see NoUnlockedActiveSessionForAttended.
SessionCreationError	400	Unattended	We couldn't create the session on the machine for an unknown reason. Check the following: - Ensure that you can remote desktop to the machine from another machine on your network. If you're using a Windows server, you can try to remote desktop to "localhost" from the local machine itself when logged in as another account. If these fail, use general remote desktop troubleshooting. - Ensure that no third-party software is installed that may affect login or interfere with creating a remote desktop connection. - If you have a legal notice enabled for login, work with your system administrator to try disabling it.
SessionCreationWinLogonFailure	400	Unattended	We can't create a Windows session to run your unattended desktop flow. You need to restart your machine.
SessionExistsForTheUserWhenUnattended	400	Unattended	Check that you aren't logged in with the same user (regardless of the state of the session) on the machine. For more information about this error code, see SessionExistsForTheUserWhenUnattended.
SessionNotFound	400	Unattended	The Windows session on the machine for the given run can't be found. This issue can occur in the following cases: - The machine reboots during the run. - You're using a virtual machine that was cloned after installing Power Automate. If it was cloned after the installation and was registered, delete your machine from the Power Automate portal and re-register the machine.
TooManyActiveSessions	400	Unattended	Windows Server only. You need to sign out at least one active session on the machine.
ExistingRecordingSession	400	Local	Windows Server only. Check that there's no other user connected to the machine launching a recording or a test playback.
LocalPlaybackOrRecordingOngoing	429	All	Check that there's 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	Attended Unattended	A desktop flow is already running on the machine. You need to wait for its completion. For more information about this error code, see UIFlowAlreadyRunning.
AadLogonFailure	400	Unattended	You need to disable Network Level Authentication (NLA) on the machine if you want to use Microsoft Entra credentials.
Win10AlreadyHasActiveSession	400	Unattended	Windows 10 only. You need to sign out from the active session on the machine.
UIFlowAgentNotAvailable	400	Attended Unattended	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	Attended Unattended	You need to ensure the revocation list for the certificates can be checked. Ensure that the CRL services aren't blocked on the target machine. The services that must be contacted are listed in this article: Limits for automated, scheduled, and instant flows
NoListenerConnected	404	Attended Unattended	The endpoint wasn't found. There are no listeners connected to the endpoint. Check that your machine is online.
ConnectionNotEstablished	404	Attended Unattended	The endpoint wasn't found. None of the connected listeners accepted the connection within the allowed timeout. This error code can be caused by routing or firewall configuration issues. Check that your machine is online and can communicate with the required Power Automate endpoints.
DnsError	404	Attended Unattended	The endpoint wasn't found. Register your machine again and schedule new runs.
ConnectionTimeout	404	Attended Unattended	This request operation didn't receive a reply within the configured timeout. Check that your machine is online and can communicate with the required Power Automate endpoints.
EndpointDoNotExist	404	Attended Unattended	The endpoint wasn't found. Register your machine again and schedule new runs.
GroupIsEmpty	400	Attended Unattended	The machine group is empty. Add machines to the group, then reschedule new runs.
NoCandidateMachine	400	Attended Unattended	The run has exceeded the queue waiting time limit. Consider allocating more machines or spreading desktop flow runs to optimize wait time in the queue.
DesktopFlowsActionThrottled	429	Attended Unattended	The desktop flow action failed because of throttling. This error code appears when too many desktop flows use the same connection. Check your connection usage and assign your desktop flows to multiple connections.
DesktopFlowsActionTimeout	400	Attended Unattended	The execution of the desktop flow action exceeded maximum duration. Increase the time-out value that's set on the action or split the desktop flow into several shorter desktop flows.
OnPremiseDataGatewayNotAvailable	502	Attended Unattended	This error code only occurs when using an on-premises data gateway (deprecated) to connect to the machine. Check that the targeted machine and the data gateway on that machine are up and running.
AuthTokenNotYetValid	401	Attended Unattended	This can happen if the group password is created from a machine that has a clock indicating a time in the future for the machine that sent that error. Please ensure that all machines have an up-to-date clock and retry in a few minutes.
UIFlowAgentLauncherServiceIsNotRunning	500	Attended Unattended	A required service is not running on the target machine. Please ensure that the Power Automate agent launcher service is running on the target machine.
TotalChunksMismatch	400	Attended Unattended	When sending the required data to run the desktop flow, a corruption was detected. - Ensure that there is enough free disk space on the target machine to run the automation. - Ensure that the network connection is stable during the automation. - Consider reducing the size of the script to reduce the risk of a chunks mismatch error. - If the issue occurs consistently for every run，and you're running Power Automate version 2.36 or later, check if the cache folder C:\Windows\ServiceProfiles\UIFlowService\AppData\Local\Microsoft\Power Automate Desktop\Cache exists. If it does, stop the runs from executing, and then delete the cache folder with administrator permissions.
DesktopFlowMalformedMachineResponse	500	Attended Unattended	This error code occurs when the target machine provides an unexpected response to the cloud orchestrator. - Verify that the machine has sufficient compute and memory resources while running the automation. - Ensure that the network connection is stable during the automation. - Ensure that you have the latest version of Power Automate for desktop installed.
WcfServerCrash	500	Attended Unattended	This error code occurs when the machine encounters an unexpected error while answering the cloud orchestrator. - Verify that the machine has sufficient compute and memory resources while running the automation. - Ensure that the network connection is stable during the automation. - Ensure that you have the latest version of Power Automate for desktop installed.
DataverseTimeout	504	Attended Unattended	A desktop flow has been triggered and then failed due to a time-out of a Dataverse call. Take the following steps to solve this issue: 1. Scale up your Dataverse instance. Contact your administrator for assistance with this step. 2. Identify the heavily used Dataverse instance. The Dataverse call might be affected by other users using the same Dataverse instance in parallel. 3. Contact Microsoft Support for further assistance if this issue persists in your environment.
RdpPermissionNotGranted	400	Unattended	This error occurs when the user specified in the connection doesn't have permissions to create remote desktop sessions on the machine. - Verify that the user in question is included in either the Administrators or Remote Desktop Users group on the machine.
XrmMachineGroupNotFound	404	Attended Unattended	This error occurs when the machine group has been deleted. Please re-create the group and update the connection.
SessionCreationInvalidCredentials	400	Unattended	This error occurs when the unattended session couldn't be created with the provided credentials. This issue might occur due to an incorrectly formatted username. For Microsoft Entra joined machines, ensure the username is in the user@domain.com format. For domain-joined machines, the username should be in the domain\user format.