Notes keeps crashing in Sierra. Please help!

Did NOT work for me. Every time I try to open the app I get the error log saying "Notes did not open because of a problem" followed by details which can only possibly be understood by a software engineer.

I found the real problem to be a mail account that could not log in.

That is why it works in airplane mode.

Disabled the failing email account and it is all OK.

This is most definitely a Apple BUG still ... :::

Shut down your computer reboot. Launch Notes but don't use the tutorial.

Thank you SO MUCH for posting this. I experienced the same problem after attempting to update a note (my guess is that update "corrupted something" and I could not re-open notes without it immediately crashing. A Google search for "Apple Notes Crashing" "Sierra" led me to this thread and I did your above uncheck-open blank-re-check and it has fixed the problem for me too.

Thanks, citizenleroy. You're the man!

Had the same problem after upgrading to Sierra. Notes opened just fine. However, the second I started to edit a note, the app crashed. I tried to reopen it several times. The app would only stay open for a split second and, then, crash again.

Another fix I found, while Googling the problem, was to go into Notes through iCloud.com and edit a note, there. Then, I was able to reopen the desktop app and it was working fine.

It appears something got broken in the line of communication between iCloud and the desktop app.

On a related note, I have (even since the days of El Capitan) sometimes had issues with some notes not syncing properly between devices. Most common is I open Notes on my Mac desktop and find that notes I have added earlier on my iPhone do not come into the Mac. When this happens, if I sign into icloud.com through a browser and access my Notes there, it (most of the time) causes the additional notes to start syncing from the phone to the Mac desktop. (I have all three open when I do this and can watch it happening miraculously before my eyes). If it DOESN'T solve the problem, then I believe citizenleroy's solution to the original problem in this thread would also solve that issue as well.

My Notes crashes after the Sierra update also. However, I found a work around by enabling the Airplane Mode. Then I'm able to read / write in Notes. Then I disable Airplane Mode. I haven't checked if any of my info synced had synced to iCloud or not. I hope this get resolved soon!

I've found that Notes crashes whenever I enter a special character, for example a link, or ½. So far I've been able to open Notes on my phone and delete the offending character, but it certainly would be nice if this didn't happen.

Interesting!