Error in Packaging my Game

hI GUYS, peaaaaaase help me with this issue.i made a BP project but when i package my Project i get this error message everytime “LogUObjectGlobals:Warning: Failed to find object ‘Class None.’
PackagingResults:Error: Error Unknown Cook Failure” . please if you can find a solution to this. THANK’S

i have an actor in my level which the reference of it deleted from your content browse