Display resolution keeps changing


We currently have 4 private webpagetest agents that are hosted in the UK. We recently added the 4th in order to run more tests, the setup of the OS (Windows Server 2008 R2) and WPT ini are identical to the other agents. The only thing that is different is that the new agent has iDRAC installed in order to offer KVM functionality.

We want to run the resolution at 1280x1024, however I have noticed that when wptdriver runs I get locked out of iDRAC with a signal issue, at the time this happens wptdriver reports ‘Installing software’. I can still RDP to the agent, however the display resolution has changed automatically to 1600x1200.

I have restarted the box countless times, edited the registry to ensure 1280x1024 is forced (I followed suggestions here https://social.technet.microsoft.com/Forums/windows/en-US/4e074fdc-4a49-450a-ae4f-2d17f186a8d2/resolution-changes-after-every-reboot). I’ve checked the event logs and there are no errors or warnings reported.

Is there something within wptdriver that could change the display resolution? Is there something it installs that could cause this issue? Has anyone seen a problem with iDRAC that would cause this to happen?

I’m almost at the end of my tether and am considering asking the server provider to clean the box down and start over again - however this is a last case scenario as it takes the best part of a day to get an agent configured correctly.

Any suggestions welcome.



If you are running a reasonably recent version of wptdriver you can add “Keep Resolution=1” to the [Webpagetest] section of wptdriver.ini to keep it from changing the desktop resolution.

Usually it tries to go as high as possible up to 1900x1200 while still keeping 24-bit mostly so headless and cloud instances can still have reasonable desktop sizes.

Thanks Pat, I had no idea wpt sets its own resolution, nor did I know about “Keep Resolution=1”.

Is there a place where changes such as this are listed? Or even a WPT scripting reference?

Not really, beyond the private instance sites page. I’ve been planning on moving the pages to GitHub so it would be easier for people to contribute documentation/changes.

For scripting, do you mean the browser automation? That does have a reference page: https://sites.google.com/a/webpagetest.org/docs/using-webpagetest/scripting