Question / Help Solved (UAC and screen capture): Windows capture failing (occasionally working)

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Silenus

New Member
I post this in case anyone else has this issue. I could find no errors in the logs.

Issue: When trying to capture my main monitor the capture appears blank (transparent) with no output, everything else working as expected.

After going through lots of testing to try and see what was causing it (GSYNC, refresh rates, websockets etc etc etc) I finally found what causes it and a fix (or workaround if you like)

I noticed that it didn't happen when I didn't start streamlabs chatbot up (always started after OBS so my websockets script can connect).
Chatbot was causing a UAC screen dimmed dialog box to pop up and at this point my monitor capture stopped working, it seems this 'screen dimming' stops the capture from working (again no log errors were seen).

When changing the UAC to not dim the screen the issue goes away.
When starting up chatbot before OBS the issue goes away (but requires manual reconnection for websockets script to work in my case).
I tried another program that prompts for UAC authorization and it produced the same result.

I did search but didn't see this issue with anyone else so it might just be my odd setup (or bad searching technique). Just posted so others may find it if having the same issue.
I may also have posted in the wrong area. I only just created an account to post this fix, in case it helps someone else, as I was having problems finding an answer through web searches.
 
koala

koala

Active Member
The inability of OBS (and any other screen recording software) to capture the dimmed UAC prompt is by Windows design. It's no flaw in the recording software. Windows denies all screen access during the prompt. You cannot work around it. If you need to perform steps during recording that produce the prompt, do these steps before starting the recording.

By the way, apps that require UAC authorization that are not Windows debuggers, Windows system management+configuration, or install/deinstall programs are bad. Don't use them, if you cannot make them run without UAC authorization. No decent app, no decent game needs UAC authorization except at install time.
 
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Silenus

New Member
Thanks for the reply.
I understand this isn't an OBS issue. I don't know why streamlabs chatbot prompts UAC but I find the tool invaluable so I have to put up with the prompts.
I have noticed on very rare occasions that stopping and starting the source/switchings scenes occasionally reactivates the source but mostly it didn't work.
As the issue was with the full monitor capture I never equated it to the UAC prompt. I normally got the prompt when I started everything and then sat on the "starting soon" screen for a while. I would then start streaming and it was only when I wanted to show something other than my game, and I tried enabling the full screen source, did I realize it was working and this could be hours after the prompt had popped up. This is why it took me so long to realize this is what was causing it.

I mainly posted this as I wasted a lot of hours in the last few months searching for this issue and how to fix it but never found anything on this particular issue (could be my inability to search). I'm just hoping to save others that time as they may now find this post and the workaround.
 
YorVeX

YorVeX

Member
The big issue here isn't that the UAC screen cannot be captured, I'd be fine with OBS just showing a black screen or a screenshot of the last thing it could capture before the UAC prompt was activated.

The real problem is that after the UAC prompt is gone display capture is still broken beyond repair and only an OBS restart helps. For others stumbling on this I created a bug report here.
 
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