failed to publish
It's probably the steam client connection to the server, not the actual internet.
My friend said he had to rename it to something he had already uploaded, but It didnt work too well for me. Could be worth a try
I think you might be onto something, because it worked when I re-uploaded a previous map. I'll give it a try.
Hmmmm... what about publishing a PTI map (just a small one so it can be done quickly) and then update it with a bigger (and maybe hammer) one? is this also hapenning with publishing from the PTI creator?
useful tools and stuff here on TWP 
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[/spoiler]Unfortunately PTI maps weren't working either. It was only maps that I'd already uploaded that would work. Publishing via PTI does work, though it didn't for a bit (I think that was just connection issues).
Fortunately, though, I was able to upload my map under the same name as another map (in a different directory) and that worked fine and the map uploaded. Hopefully this issue will go away, though, because I'd like to keep the map names proper for the sake of orderliness 
This is so annoying. I'm not sure about what is happening to the p2map_publish.exe, but I can't publish the map to my workshop... Yesterday I was trying some map-replacement maneuver but as long as you restart steam and the cloud notices it, it replaces the map back... Grey made a few attempts to publish too and it seems to be working for him, although it was a PTI map modified in hammer... could it be related to hammer maps mostly? did VALVe decrease the max file size allowed recently maybe? maybe too much custom content matters now?
useful tools and stuff here on TWP [spoiler]
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I haven't been able to upload maps either, and I've renamed my map file, reuploaded multiple times, and nothing worked. None of my steam friends are having any problems though.
Aperture Science: We do our science asbestos we can!
I think the little Update a few days/week ago corrupted some Files. For example when you exit Portal 2, I hate this Crash..
This, altogether with the fact that every time you verify the integrity of the local files, it finds 1 or 2 that needs to be reacquired (for both, the game and the tools) is what I think that is messing up the p2map_publish.exe tool. There is something wrong with the game after whatever VALVe did.
Even though I guess someone else surely did already, I've submitted a ticket to VALVe:
p2map_publish.exe NOT WORKING ANYMORE
I'm not sure if you are aware or not, or if any other mapper already referred to this issue before, but it's too long now since the tool to publish to the workshop is not working to upload hammer custom maps.
The game doesn't quit properly either, but crashing, and after verifying the integrity of the local files, it always finds failing files... this is not normal at all.
I'm not the only one having this issue, but it's worldwide.
Could it be that any recent update is messing up the game and the tools?
Could we know if you are on this and when do you expect it can be fixed?
Thanks in advance for the attention.
Best regards.
useful tools and stuff here on TWP [spoiler]
[/spoiler]As soon as Valve fixes this, there's going to be a workshop explosion hopefully.