I am working on a coop map, but when I compile it, no bsp file actually appears.
I looked at the compile log, and it didn't even get through vbsp.exe, with the error

Could not open Instance File instances/destruction/dest_wall_01b_128*128.vmf.

That was the last line in the compile log, other than

Finished. Press a key to close.

I looked in Windows Explorer, and indeed that instance was not there, but I couldn't see it used anywhere in the map!

If you want, here is the vmf:

mp_coop_first_map.vmf

Instances can have func_instances inside them, so check any large rooms to make sure there isn't a copy inside them. The "spawn room" or "reconstructing_panel" instances might have that instance in there. Otherwise, make a new map and save it under that name, just leave it empty to effectively delete that func_instance. That might make holes in the map appear though.

I solved the problem by making blank vmfs with the dest_wall instances, and I actually figured out where they were supposed to be. There were two dest_wall instances in the coop_spawn_room_bridge, I might replace them with the dest_floor_256*128 or make my own dest_wall instances. Thanks for the help!