Hello,
I was toying around in 4.2 and tried to replicate something I had seen in the reflection demo map.
In there a RenderTarget was applied to a 2DSceneCapture actor to act as some sort of mirror.
When I tried to do the same in my map the Editor immediately crashes and burns. 
Please find Log and crash dump in attachment.
Hello,
Thank you for your report. We were not able to investigate this on the engine version you reported, but there have been many version changes to UE4 since this question was first posted. With a new version of the Engine comes new fixes and it is possible that this issue has changed or may no longer occur. Due to timetable of when this issue was first posted, we are marking this post as resolved for tracking purposes.
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Thank you.