I followed the instructions included in many of them, and they are all the same.
Download
extract ( I put them into their own folders in Steam/Steamapps/Common)
cut .bsp file, then paste .bsp file into Steam/Steamapps/Common/Portal 2/Portal2/maps/
run steam
start game (here it is unclear whether to start new game, or continue an existing game, I did both)
enable developer console (has been for a long while now)
press the ~ key
type map <map name> (without the <...>)

But, what happens then is I get disconnected from the server, and I can't play anything until I load a new game again, or continue an existing game.

I feel like I am so close, but doing something wrong.
<---- ID10t error.

Is this a co-op map or a singleplayer map?

Also, which map is this?

all of them are SP, and I have tried Cubi, missing geodome, angrybombs, lost in testing among others.

Also, I verified the something or other, and did something to the cache too. Sorry, I can't brain tonight, I have the dumb. I will check the instructions I followed from the google search using the error messages I had originally.

originally, after loading the maps and trying to run Portal2, I had the error message "failed to load the launcher dll" and I followed the instructions to
Verify integrity of game cache...

And finally do Defragment cache files.

There is an 'edit' button for a reason...don't triple post. ?_?

Try following the playing Portal 2 maps guide located in my signature.

You just need to place the .bsp file in 'portal 2/portal2/maps'. If it is a .vpk file, place it in 'portal 2/portal2/addons/'.

If you are running Portal 2 whilst placing the .vpk type in the console 'update_addon_paths' then do the 'map ' step.

From the looks of your instructions...

dentedvw wrote:
Download
extract ( I put them into their own folders in Steam/Steamapps/Common)
cut .bsp file, then paste .bsp file into Steam/Steamapps/Common/Portal 2/Portal2/maps/
run steam
start game (here it is unclear whether to start new game, or continue an existing game, I did both)

No need to start any game, be it saved or you are creating a new one.

Once you have started Portal 2, and you are at the main menu...just enable the developer console and type 'map '.

If that doesn't work try this.

yes! that's it. use the dev console from the main menu. That wasn't mentioned anywhere, and for some reason I thought it only worked within a game. Nice.
Thanks!

Also, I didn't think I triple posted. At least, not the same thing.

dentedvw wrote:
Also, I didn't think I triple posted. At least, not the same thing.

You posted one after the other...three times...want me to count again? ?_?

Also...this means I shall update my guide...didn't think that some people would try to do it in-game.

Um it works in game. I do it in game all the time. I test other peoples maps and at the end I <map name> into the next one. Works fine.

iWork925 wrote:
Um it works in game. I do it in game all the time. I test other peoples maps and at the end I into the next one. Works fine.

Maybe it works differently in the campaign shrugs shoulders