I come here as a last resort, as this problem has already ruined two of my maps.
The error is: "The map could not be loaded because it had too many obstructions. Try widening corridors and reducing the number of nooks and crannies to correct the problem".

So, I have read the previous Nooks and Crannies threads, and I have tried their solutions to no avail. This includes copying all the terrain to a new map, removing all doodads, etc.
Now, this has happened to me with a Jungle 256x256 map and a Badlands 256x256 map, and I have not used extensively complex terrain. Far less complex and with less tight corridors than that Crescent Dyne terrain anyways. I do use a lot of isometrical terrain, and a smaller amount of square terrain for inside buildings.
I cannot stress how incredibly frustrating this is, as I have already completed the majority of my triggers, and I haven't even finished the terrain. There is still around 1/6 left to go for terrain.
How does Blizzard expect us to use 256 by 256 size maps to their full potential if they are going to censor how much terrain we can actually use?

Anybody with any suggestions at all to fix this pain in the ass of a problem would be very helpful.

I think it has to do with the unit pathing/AI.

Post the map and maybe we could give you some suggestions.

i had this problem too on a 256x256 jungle map and i redid the whole map and had it again, and i found later it was because i was placing too many custom doodads, like tiles put together from other doodads, if you even everything out, like doodads and custom doodads and terrain, it should work. Thats what they do in crescent dyne, also crescent dyne was made by a bunch of crazy good mapmakers who knew secrets beyond map editors. for example their terrain isnt isometrical if you try to place a isometrical peice of terrain on it it'll go null. But yeah im blabbing, just even everything out. And dont get carried away with doodads and custom doodads even though it looks pretty sweet on crescent dyne.