Hello there,
The past day I am seeing this error in my dev console all day today and at first I thought it might of been something wrong with my code that I added but I couldn’t see anything wrong. Anyways here is the game it’s happening for me Game I’m not sure if it’s happening within the games places.
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Sorry for the inconvenience, unfortunately this was a regression that went out in the latest release.
We have a fix for the regression merged already that will go out next week.
This is happening in any game which disables the Captures CoreGui type.
-- Either by disabling Captures specifically
game:GetService("StarterGui"):SetCoreGuiEnabled(Enum.CoreGuiType.Captures, false)
-- Or by disabling the All CoreGuiType
game:GetService("StarterGui"):SetCoreGuiEnabled(Enum.CoreGuiType.All, false)
While there is an error printed in the output it’s an internal CoreScripts error which should not cause any issues with the functionality in your experience.
When the next update is out, should remove that or leave it there for a bit longer?
I was just giving some code samples showing that this would happen if your experience is already disabling Captures, not recommending any code change to mitigate the issue.
If you want to prevent the output you could allow Captures to be enabled in your game. But the error is harmless and won’t cause any user facing impact so there is no need to take any action.
Ah okay my bad I appreciate it. 
Yes, this fix has been released as of last week. A few older client versions may still have the code with the error but the majority of users will have this fix now. As users upgrade over the next few days this error will go away completely.