Wednesday, December 6, 2017 [Tweets] [Favorites]

Month 13 Is Out of Bounds

Rob Griffiths (tweet):

But if you’re unlucky enough to be a Mac user in the month of December, 2017, then you’ll probably be seeing a lot of “Month 13 is out of bounds” messages in your Console. And by ‘a lot,’ I mean an exceedingly excessive never-ending stream of spewage…

Thousands and thousands and thousands of them—I’m getting anywhere from two to 20 per second, continuously.

Benjamin Mayo:

The plot thickens. Similar logs are generated by my iOS 11.2 iPhone, which is up-to-date. It seems like Apple patched over the Springboard crashing but the underlying calendar logic is still broken somewhere.


I’m getting this and it is causing UserEventAgent to consume all my cpu and RAM. Only solution is to set the date back until November.

William Osman:

My MacBook Pro was rinsed by UserEventAgent. Took full use of CPU and memory. I had to force quit it within Activity Monitor every ten minutes to keep laptop running.

Alexandre Colucci:

’Month 13 is out of bounds’: The official CoreFoundation ‘__CFYMDFromAbsolute’ source code is available online. You can see the new ‘ASSERT_VALID_MONTH’ define causing all the ‘Month 13 is out of bounds’ logs.

See also: Apple Developer Forums.

Previously: Rushed iOS 11.2 Update to Fix Date Crasher.

Update (2017-12-06): Stuart Breckenridge:

It’s appearing at least 20 times per second and other than disabling Bluetooth, I haven’t found a way to stop it.

Update (2017-12-08): Gus Mueller:

Wait, 10.13.2 didn’t fix the Month 13 is out of bounds problem?


Good thing: either Apple fixes it within the next week or it doesn't. In not even 4 weeks January will hopefully silent the bug.

Patrick J Mele

submitted Bug Report to Apple Developers

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