This could be a variety of things. If you’ve built the Unreal Engine from source, you may have to compile CrashReportClient. Or if you’re packaging for shipping, make sure you’ve built for shipping. If you’re using stock Unreal Engine, then it could be several different problems. It could be an issue with assets. Check that your map sizes aren’t too big. I’ve had issues with maps larger than 500 mb.
If you could post the specifics of your error, that would help greatly.