Power Automate Desktop installation troubleshooting

Cause

The install fails because the Power Automate Windows service failed to start, and the event viewer logs show that the reason it could not start is "System.DllNotFound Exception: Unable to load DLL 'uiflowsclient.dll'"

Workaround

Uninstall Microsoft Visual C++ 2015-2019 Redistributable

Go to Settings > Apps > Apps & features and uninstall it, then re-install Power Automate Desktop. The Power Automate Desktop installer will reinstall the C++ redistributable.

Cause

The installer grants permissions to the Power Automate service to enumerate user sessions on the machine. These permissions may need your machine to be rebooted to take effect.

Resolution (installer version 2.18 or greater required)

This issue can be worked around by skipping starting the Power Automate service during the install, and rebooting the machine right after install. This can be done by passing the /SKIPSTARTINGPOWERAUTOMATESERVICE argument to the installer:

If successful, you will see that the Power Automate Windows service is successfully running after the machine restart, and is no longer crashing and emitting the "failed to enumerate sessions" error seen in the event log.

Cause

There is likely an issue with your machine not allowing the Windows account of the Power Automate service (NT Service\UIFlowService) to be created during the install.

This can be confirmed by running the install again, and checking if the account exists while the installer is attempting to start the Power Automate service. The account's profile should be found in the registry here: "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList\S-1-5-80-3017052307-2994996872-1615411526-3164924635-3391446484

If this registry key doesn't exist, your machine isn't allowing the service user account creation. Note that when Power Automate desktop is not installed it is expected that the key doesn't exist, its existence needs to be checked during installation.

Resolution (installer version 2.18 or greater required)

There is a workaround that requires providing a Windows user account that will run the service instead of the default account. This account will need to be a member of the remote desktop user group, and will need to have the "Logon as a service" privilege.

You can run the installer and skip starting the power automate service by running it from the command line and passing it the /SKIPSTARTINGPOWERAUTOMATESERVICE argument

When the install succeeds, run the Power Automate machine runtime app and use the troubleshoot menu to change the service account.

Cause

The account used to start the Power Automate service is unable to start the service because the "Deny log on as a service" policy prevents it.

By default and during installation, the UIFlowService runs as NT SERVICE\UIFlowService. The account used by UIFlowService can be changed later, but for installation purposes it must not be blocked from logging on.

Resolution

Update the "Deny log on as a service" policy to remove the account or group that prevents NT SERVICE\UIFlowService from logging on as a service.

Example: Everyone

Cause

The Power Automate installer depends on the LanmanServer service and attempts to start it if it isn't already running. If the service cannot be started, installation steps that depend on it will fail and the install will fail too.

Resolution

In the services manager (Windows key + R services.msc or services in the start menu), find the service named "Server", right click it and select properties. In the general tab, make sure that its startup mode isn't disabled (it should be automatic by default). Click "Apply" to update the startup mode.
You can then start the service manually by right clicking it in the services manager tool and selecting "start". Once the service is running you can attempt the installation again.

Cause

When installing Power Automate binding an SSL certificate to the http port used by Power Automate failed..

Resolution

The SSL cert is only needed for On-Premise Data Gateway connectivity, if youd don't require it, starting with the 2023 May release (ver 2.32 or above), it is possible to skip the install steps required for for On-Premise Data Gateway connectivity support by running the install from the command line with the /SkipGatewaySupport parameter.

If you do require Gateway support, you can get more details as to the root cause, run the following PowerShell commands. One of them should fail with a specific error code which will give more insight on how to mitigate the issue:

$sslport = 4723
$applicationId = [string]::Format("{{{0}}}", "33BEDDD1-E697-4606-B306-C5DFE7AE0AAE")

$serviceUser = "[USER account]" # TODO: fill with domain\alias
$thumb = "[Certificate thumbprint to bind - certificate located in LocalMachine\My cert store]" # TODO: fill certificate thumbprint

function ExitIfError {
    if ($LASTEXITCODE -ne 0) {
        exit 1
    }
}

Write-Host port: $sslport; thumb: applicationId=$applicationId

Write-Host [2] Adding all IP addresses to the IP listen list
netsh http add iplisten ipaddress=0.0.0.0

Write-Host [3] Trying to remove the previous certificate on port $sslPort
netsh http delete sslcert ipport=0.0.0.0:$sslPort

Write-Host [4] Binding port $sslPort to certificate with thumbprint $thumb
netsh http add sslcert ipport=0.0.0.0:$sslPort certhash=$thumb appid=$applicationId verifyclientcertrevocation=disable
& netsh http show sslcert ipport=0.0.0.0:$sslPort # displaying the cert binding

ExitIfError

Write-Host [5] Giving access to https://+:$sslPort/UiFlowDispatcher/ to user $serviceUser
netsh http add urlacl url=https://+:$sslPort/UiFlowDispatcher/ user=$serviceUser