It's happening to me since the last update and I'm unable to play any game. When I click the Steam icon, it opens the "Updating" bar, which sits at 0%. Then, the app closes, a second Steam app instance opens, and the error pops up with this exact text:
Steam.exe (main exception): ERROR: copying SteamNew.exe to Steam.exe failed, Win32 Error 32 "The process cannot access the file because it is being used by another process."
I've restarted my computer normally and in safe mode, and there don't seem to be any processes legitimately tying up the app. I know I'm not the only one with this issue, as I've seen the question popping up here and there.
Does anyone have a solution that doesn't involve deleting all of my game data?
I'm on limited bandwidth so I can't afford to download everything again
Best Answer
I discovered Steam's "Repair tool" in the installer. I'm not sure if it matters, but during my earlier troubleshooting, I deleted everything in my Steam folder except for steamapps, userdata, and "Steam".
The Repair tool ran for quite a while (it seemed to be stuck at the end) and then when it was finished, the update went off without a hitch. It took a few minutes to remember that I'd already downloaded most of my games, but it seems to be in its original working order!
I'm not sure why they don't mention this at all in their troubleshooting article...