Perpetual Testing Initiative
I'm re-installing portal 2 now hopefully that does something. Hopefully.
EDIT: It does nothing still crashes on boot. NOT COOL.
Mine's downloading!!!! 
Question: It's trying to update Portal 2 Authoring Tools. Does it need to update that in order for the editor to work properly? It slows down the Portal 2 download if I turn that one on. So, I would like to wait to update that until Portal 2 is done. But, if the editor needs that update, I may as well have them both going.
I recieved an update to the authoring tools just a short time ago.Maybe that fixed your issue?
Edit- Nope I checked mine and it crashes also
Hammer wont run for me either. Also, I don't know if its just my files or the game, but I cannot rebuild the map in game in order to test the setup. The editing tools seem to work fine, but the moment I hit F9, it says there is an error and it won't say what.
oh no. i started up steam ANd it started downloading it. now that i know what it does, i dont even want it anymore. 
if anyone finds out what files to remove or a fix to the issue so hammer works again, i will gladly download it. otherwise, this is going to wait.
Aperture Science: We do our science asbestos we can!
Hammer issues can be solved using this post
I've got a temp fix:
Download and extract this to something like common/portal 2/bin_old - DO NOT OVERRIDE, IT WILL BREAK PORTAL 2. Copy your current bin folder to something like bin_new.
When you want to use hammer, rename bin_old to bin. When you want to test maps or play portal 2, switch it back and rename bin_new to bin.
It's a bit annoying but at least you can use hammer.
Side note: the old one doesn't include the updated vbsp.exe or portal2.fgd, so you might want to copy those over from your new bin folder.
found here.
mapping-help/hammer-not-starting-after-dlc-update-t6146.html
It isn't perfect but it's good enough for science.
When will they fix the custom-map publishing and the workshop management?
In the workshop there is no option to upload anything, or to delete anything, and the p2map_publish.exe never worked (same as 1 month befora in the beta), gives an error:
"Steam cloud does not appear to be available!"
In the workshop there is no option to upload anything, or to delete anything, and the p2map_publish.exe never worked (same as 1 month befora in the beta), gives an error:
"Steam cloud does not appear to be available!"
I think you need to email them about that, they didn't have time to dig around that issue because I think the main idea was to make the puzzle maker and release it by the deadline.
If this problem keeps happening, they said to contact a steam engineer, and they can help you.
A FIX WE FOUND THAT WORKS: remove the the authoring tools under tool section in steam program, verify portal 2 cache, reinstall authoring tools.
In the workshop there is no option to upload anything, or to delete anything, and the p2map_publish.exe never worked (same as 1 month befora in the beta), gives an error:
"Steam cloud does not appear to be available!"
I think you need to email them about that, they didn't have time to dig around that issue because I think the main idea was to make the puzzle maker and release it by the deadline.
If this problem keeps happening, they said to contact a steam engineer, and they can help you.
Have you got the email of a valve person who works on this? I have the same issue with p2map_publish and few others do as well, maybe everyone?