Easy click on the mesh in the level. Try to open it. It will say ‘there is no physics asset for this mesh, would you like to make one?’ you click ‘yes’. Follow the prompts.
Or,
Right click static mesh in content browser, select 'create > physics asset > create ’
Then you have to go into the static mesh and make sure to assign the new physics asset you just created to the static mesh.
Bam error gone!