Office 365 sometimes unable to start

I can confirm Killing the click to run task and then restarting excel worked for me too. Thank you for that tip as it saves rebooting when it happens. This is a truly annoying bug with 365 that MS obviously has no interest in addressing given that I’ve raised it countless times with them in various ways (their forum/twitter etc) with little or no response. Suspect the catalyst is 1809 windows as I don’t believe I ever noticed it before then.

You could be on to something about 1809. It never happened before the update.
Strangely my work computer has never had it happen and it it gets the most use.

Maybe the next feature updates (as much as I dislike the regularity of them every 6 months) will stop the issue. My patience with Windows 10 is very low with the mountain of bugs and I think the regular feature updates just seem to pile more bugs on top of bugs whilst often removing things that I actually liked (remember those Cortana cards, I liked them til MS ripped them out in 1803)

i guess the good thing is your work machine is dodging the issue

Not just windows 10. Had a Windows 7 machine do exactly the same thing.
Restarted the click to run service & all good.
When i restarted the Click to run service it threw an error about a named pipe being closed. ( I think it was a named pipe, was in bit of a hurry and don't remember the exact error ) This problem gets more interesting.

It's a complete farce. over the months I have tweeted Office support and posted to that usless MS answers forum and also filled feeddback so many times. But nothing ever gets acknowledged or done. They are utterly hopeless. Fed up with Microsoft. It's reasonably widespread as I have some friends report the same. But many people I know have office proper rather than this 365 and don't notice the issue or at least haven't informed. I think 365 users are still in the minority

It actually pulled this stunt on a retail copy - Not 365.

Interesting. So the bug festers within all office versions.