We're sorry. OneNote is cleaning up from the last time it was open. Please wait.

Relaunch OneNote after quit OneNote application. Sometime catch the follow error message:

We're sorry. OneNote is cleaning up from the last time it was open. Please wait.

Sometimes OneNote cannot relaunch thought it scroll to end of progress, and pop up message:

It looks like OneNote is having trouble starting right now. If you keep seeing this message, restart your computer and start OneNote again. We're sorry.

If OneNote show this message, It mean that you have to restart your computer to recovery the OneNote start problem.