Travel error, invalid url

Warning TravelFailure: InvalidURL, Reason for Failure: ‘Invalid URL: /Game/maps/mainmenu’. Shutting down PIE.
Warning TravelFailure: ClientTravelFailure, Reason for Failure: ‘Invalid URL: /Game/maps/mainmenu’. Shutting down PIE.
this is the output log for when i try to use my main menu, the weird thing is, i can load my main menu fine, it is when leaving my main menu that the error occurs, any help?

try to reload the engine or restart it, if it keeps happening try using Standalone game