Unattended flow

(3) Share

Report

Posted on by CU28050906-0

Hi, Im running a power automate desktop flow unattened on a virtual machine using power automate online the flow has only 2 actions, a reacurrance (every hour) as trigger and run desktop flow (consists in refreshing a power BI report and exporting a csv from it) this was running without any issues in version 2.55.158.25087 version of power automate desktop, but when i updated to 2.56.232.25124 it started failing everytime, the error was "failed to assume control of the browser" and now on the version 2.56.239.25132 it gets a mix of random runs (successful/failed) and when it fails is on action "press a button on webpage" this only happens while running the flow unattended, if i login in the virtual machine and run it has no errors.

I have "wait" actions throughout the flow to avoid not having the elements displaying, tried to add "wait for webpage content" nothing worked...

I have premium licence and unattend and the UI elements all checked to be workin properly.

Is this a known performance issue? Is there something that can be done to fix this?

Categories:

Power Automate Desktop

I have the same question (0)

All responses (7)

Answers (0)

Sort by

eetuRobo 4,565 Super User 2026 Season 1 on at

Like
a
(0)

Report
Copy link

Link copied!

Have you checked the failed runs screenshots? It should always produce a screenshot of the failed action where you can see if something is off with the virtual machine. So go to Desktop flow runs > select last failed run > select the last action that failed so you see the screenshot that was captured

Some times the resolution is by default much smaller on unattended run than in attended run. Especially when updating the PAD / machine the unattended resolution settings might go back to default even if you have set them to be 1920x1080 for example.
Article how to set the unattended resolution: https://learn.microsoft.com/en-us/power-automate/desktop-flows/how-to/set-screen-resolution-unattended-mode

With the error "failed to assume control of the browser" I would check that the browser extension is up to date. Try to update your browser also to see if that fixes it. Or try with different browser like (edge, chrome, firefox)

If those don't work then just roll back to the version 2.55.158.
You can download the version here thanks to @jfevia: https://github.com/jfevia/Power-Automate-Desktop/releases?page=1

Was this reply helpful? Yes No
CU28050906-0 14 on at

Like
a
(0)

Report
Copy link

Link copied!

@eetuRobo

I have set the resolution for the Virtual machine and restarted it, no improvement.

I tested with the 3 different browsers in the past, its the same for all, i dont have the "failed to assume control of the browser" error anymore, i usually go to the error screenshot as you mentioned and its on "press a button" either to refresh the power BI or to open it, i think while unattended its not getting the UI elements even tho i have wait actions to give it time to properly load the page and attended it runs pretty smoothly.

I will give a try to the 2.55 version in the next couple of days, thanks for sharing the link.

Was this reply helpful? Yes No
Suggested answer

VishnuReddy1997 2,666 Super User 2026 Season 1 on at

Like
a
(0)

Report
Copy link

Link copied!

Hi @CU28050906-0 ,

Can you please Reinstall the browser extension and check this may resolve your issue.

Regards,

Vishnu Reddy

Was this reply helpful? Yes No
CU28050906-0 14 on at

Like
a
(0)

Report
Copy link

Link copied!

Hi @VishnuReddy1997

I have tried without success

Was this reply helpful? Yes No
Suggested answer

eetuRobo 4,565 Super User 2026 Season 1 on at

Like
a
(0)

Report
Copy link

Link copied!

Okay so when you run the flow in unattended it fails always in "press a button on webpage" -action when the flow is supposed to press Power BI refresh or open button. And you can't see anything weird or different going on in the fail screenshot vs when you run I attended. In the screenshot you can see the button that was supposed to be pressed?

Can you open the element selector and screenshot it and share it here? So we could try to point out something that might change in the UI element and make suggestions to make it more reliable.

Try to test the element to see if it gives green check mark or symbol that tells that it can find multiple same elements:

https://learn.microsoft.com/en-us/power-automate/desktop-flows/test-selectors

If it gives green check marks maybe add another selector in the one that you are using. So select New and recapture the button. Then modify it a little so that its might be little be more "loose" selector so not as specific.

So for example if I had something like this:

I could add much looser selector like so:

Now when the PAD uses this full selector it first tried the "Default Selector" and then if that fails it tried the "Default Selector 2"

For more robustness you can add "Image as fallback" and capture the button so it will be saved as an image. So if those selectors fail it will still try to find the element by image. Its not very reliable since even one pixel change can make it fail but worth adding still.

Was this reply helpful? Yes No
CU28050906-0 14 on at

Like
a
(0)

Report
Copy link

Link copied!

Hi @eetuRobo

I have every UI element in the flow in green

I can try add a 2nd one more "loose" as you are suggesting.

I have the flow running every hour even though most of the time it fails and have made very small changes in the flow and the last couple of days the error is due the page not loading, this is the screenshot from the most recent errors

I already set the timeout to 5 min, shouldn't take nowhere near this much to open

Was this reply helpful? Yes No
Suggested answer

eetuRobo 4,565 Super User 2026 Season 1 on at

Like
a
(0)

Report
Copy link

Link copied!

Then that seems to be clear reason why the flow fails.

You need to figure out from your flow logic and logs why the browser is suddenly in the about:blank -page in unattended run.
Does that happen when the browser instance launches or at some point when your flow has navigated in the site?

I suggest you add "Take a screenshot" -actions around the flow so you see every step in the unattended run and can there for figure out where everything goes wrong. So I would add screenshot action after every navigation in the web page to see if it loads correctly.

Was this reply helpful? Yes No