I even had my old pc die with the latest maps not backed up.
so put the old P.C.'s hard drive into a hard drive dock, which I connected to my new pc.
then copied the maps from my old P.C.'s drive, into portal on my new pc. successfuly :)
ps. steam will restore everything portal, exept the puzzles / maps.
so only need to back up maps.
hope this helps.

well just open portal & go to "create test chambers" & see if your maps are there.
if they are, when you click edit, you might see a new chamber, if you do, you have to click build. then you will see them as they were, probably not before.
I just backup puzzles, which are the maps.
after installing steam & portal on a new PC or O.P. (I successfuly done both)
I locate the puzzles on the new PC or O.P. (using the path I mentioned earlier)
then replace the puzzles with my backed up version. (copy & paste from backup)
I do this with steam & portal closed.
then start portal, but you must rebuild the chambers,
as they always appear as new ones, after you click edit, until then.

Well, I copy pasted all my steam folder after the update so I suppose it should work then ^^

if you backed up your maps, no problem.
if not, in future here is the path to find them:
path to portal 2 maps on a windows 7 home premium 64 bit pc.
start / computer / C drive (or which ever one your operating system is on) /program files (x86) / steam / steam apps / common / portal 2 / portal 2 / puzzles.
copy them to an external hardrive, flashdrive etc.
then with a new os or pc, instal portal & steam.
use the path to find your maps / puzzles.
then replace them with your backup version.
hope this will help ?

Hehe ^^ Thanks all for playing!
Not sure if I can still update the map after changing my OS anyway...

Very nice map. Too much thinking will distract a player from the obvious simple solution. So I had an advantage over most. I don't do much thinkimg. Ha Ha. Thank you for the fun. See ya round the workshop.

After completing it, I think it wasn't hard, but at the beginning the companion cube had me stopped for a while. And maybe I was looking for too complicated solution (cube destroyed and alive at the same time)

Geneosis
another good map.
I missed the solution for a while.
then I could not believe I did not see it earlier. (isn't hindsight great)
the sad thing is, that I was moving the bouncy gel away from the button.
to place it near the exit, without thinking it is no longer falling on the button.
when I got this part, it all fell quickly into place :)
thumbs up again.

I have a new map. when you get time, please let me know what you think:
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=143995088
map name:
cube shortage

@Frosty Andy, you can simply portal the cube over there, one under it one on the wall, and then get the funnel

All light strip placements in my maps are expected ^^ So this is intended to prevent the player from using those surfaces ;) About the distracting companion cube, I think I will remove it yeah...

Nice map. Things I found bad on this map are 1) this cube room over the grill - insanely jumping cube sound is little annoing and there is no way to get this companion cube, which makes me sad, I think only grill needs to be there; 2) lamps near the cube dropper are good signs, but they made white tiles not usable, only way to put cube in the top button is to shift the funnel to the button direction

Very nice simple chamber #F4F

Good puzzle. It's much easier than I expected, but still great for beginners.

Hint if you are stuck: This puzzle has nothing to do with flinging or momentum.