I'm getting an error for 503: Proxy Target Missing when I go to open any of my existing notebooks or start a new one.
Just keeping the notebooks open lands me in the tarpit every day before I log in, and I thought that may have been an issue. So yesterday I deleted all ongoing processes and hoped it work today. It did not.
I also feared my file was corrupted, but everything was still there when I downloaded and opened with notepad.