I was busy collecting money for Help For Heroes on Friday, but left the main desktop computer running. It seems that about 11:14am OneDrive was updated. I had previously been running 18.091.0506.007, but Microsoft delivered (on a rollout from Office 365) 18.111.0603.0004.
The net result was that OneDrive stopped working, and wouldn't restart or re-install; or even uninstall. If I could get a "not logged in" grey OneDrive icon, the right click menu was just a white space. Not good when I was trying to do some quick work on Sunday night. A support call on Sunday evening to O365 tried all that I had tried, plus a few other things but left it broken. I ended the call past midnight, and was expecting a follow up from Microsoft on Monday, yesterday. Nope, nothing happened.
Checking my OneDrive folder, there was indeed no OneDrive.EXE file present, so I copied it from the 18.111 subfolder and tried again. Nothing.
I then ran the OneDriveSetup.EXE from within the 18.111 folder and it seemed to work.
Logging into OneDrive and it started the "new user" setup. TAKING CARE TO SELECT THE SAME FOLDER AS BEFORE (to avoid re-downloading everything 😊) OneDrive for Business then decided there we more changes to the folder structure than there were files. But I let it proceed – it seems it was cross checking cloud and local copies and each file on either side created a "check".
I had to open settings and add an account to get OneDrive consumer back up and running, and it went through the same painful checking process. Currently both are still checking, but hopefully within an hour or two all shall be well.