Frequent editor crashing with 4.9.1

Since updating to version 4.9.1, after pressing the play button, the Unreal editor crashes after almost every single code or setting (actor component) change I make. This is the error message I usually get:

Fatal error: [File:D:\BuildFarm\buildmachine_++depot+UE4-Releases+4.9\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp] [Line: 83] 
SECURE CRT: Invalid parameter detected.
Expression: Unknown Function: Unknown. File: Unknown Line: 0

Also, each and every time I compile the code in VS after making some changes, a whole new bunch of DLLs are generated most of the time. I keep having to close the editor, delete the DLLs, re-open the project and let the editor rebuild from there before I see any changes due to my amended code. Is this linked with the above?

Could anyone confirm if they too are on the receving end of this problem? Is there anything I could do to fix it?

No one has any idea?

I googled the “Secure CRT: Invalid parameter detected” when I encountered the problem and found this thread. The root cause in mine was a typo in a UE_LOG entry. I Typed only a “%” when I intended a “%s” fixed it and the problem went away.

Hope this helps the next person that stumbles across this.