after adding c++ code UE4 crashed while compiling it , and when i reopen it keeps crashing, please help !
I added the log file
I can’t see anything in your log file that points to the problem, so unfortunately I can’t directly help you. However, the best way to proceed if the editor crashes is to open the project in Visual Studio, switch to the DebugGame configuration (or, even better, the Debug configuration if you are using a source build), set your game project as start-up project in the solution explorer (it should already be set, but sometimes it isn’t), and then start the debugger (just press F5).
VS should either point out problems with your source code during compilation, or throw you into the debugger. From the debugger you can, e.g., use the call stack pane to figure out the path through your code that caused the crash.
Dang, this time you were faster 
Thaaaaaaanks guys it worked … This instance was causing the crash
LaunchBlast = CreateDefaultSubobject(FName(“Collision Mesh”));
do you guys have any idea why it caused a compile time error?!!
shouldn’t the instance throw the error at runtime not compile time , I think
Your Log doesn’t give any relevant information as far as I can tell. Try to open the Visual Studio Solution of your project (.sln) and hit F5 to debug it in visual studio. The editor should start, end when it crashes you can see where it crashes in the code. If you look at the call stack you might see a function of yours in there that causes the problem.
this is getting personal
Since you are using CreateDefaultSubobject i suspect this code is in a constructor? The constructors get called when the editor starts, when the map is loaded, and before you can see anything. So it crashes before you can even see the map.
Its not actual compile time! It happens at runtime.
Since your question is answered, please accept the answer. (So I get these sweet forum points :D)
Thaaaaaaanks guys it worked … This instance was causing the crash
LaunchBlast = CreateDefaultSubobject(FName(“Collision Mesh”));
do you guys have any idea why it caused a compile time error?!!
shouldn’t the instance throw the error at runtime not compile time , I think
Yeah you are right
thanks alot , I appreciate your help so much
Done , whatever I can do to help (Y) , Sir