I can tell it's some 32-bit millisecond counter without even opening the article. 49 days period is too specific.
And since I did not hear anything about MacOS network stack catastrophically breaking on any servers, the impact should be small.
this post was submitted on 09 Apr 2026
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The article describes how they immediately went to look for an unsigned 32-bit millisecond counter when they noticed it was happening around 50 days since last reboot, because they already knew that association you describe.
Interesting writeup. Fun little story about the detective work involved.
49 days period is too specific.
49.7 days is also the maximum uptime for Windows 95 and 98.
No it's not. That's just the point at which a timer overflows which could cause a problem but it doesn't guarantee one.
Headline: Exactly 49 days
First sentence of article: 49 days, 17 hours and change
2^32 milliseconds to be exact
Ah so it's an overflow bug
(2^32 ) - 1
It would have been more correct to say exactly 50 days.
These kinds of bugs have been around for ages. There was one like this in WinNT, and this was found when the OS was finally stable enough to run for as long as that...
That this bug was found just now tells me that nobody lets a Mac run for serious lengths of time...
Multiple reports on Apple's community forums and open-source projects describe symptoms that match this bug precisely:
- Apple Community #250867747: macOS Catalina — "New TCP connections can not establish." New connections enter SYN_SENT then immediately close. Existing connections unaffected. Only a reboot fixes it.
- Apple Community #252991075: "Mac Pro TCP/IP stops working." TCP completely fails, but ping (ICMP) works normally.
- Podman issue #12495: "podman machine network connectivity stalls after some uptime" on macOS 12. The VM running on macOS shows outbound TCP failure with ICMP still functional, occurring after running for multiple weeks.
Amazing that nobody so far noticed the similarities to the WinNT bug of old.
It seems to me like nobody bothered to measure how long it took to trigger, and those in the first two threads seem unaware that it is caused by uptime and not some other random thing
So, why is this being disclosed here and not a CVE reported to Apple?
While contemplating that, my Mac has been up for longer than that and it's working fine.
The Mac I had before that was up for years, also fine.
So .. what is this really about?
A lot of these new AI found bugs are proving to be nothing burgers. Just a waste of money to try and hype the latest models.
They're either in old code not actually used anymore or miss a system interaction that fixes the supposed bug or just straight up are wrong.
LLMs are shit
Yeah, macOS, like most UNIX/BSD and Linux systems (even NT systems), use BSD‘s rather ancient TCP/IP stack. And, like most systems, have found their own unique ways around whatever bugs once existed (or still exist) in that stack.
This case uses iMessage as an example, and it would be kind of foolish not to think that between the TCP/IP stack and macOS‘s internal messaging system there isn’t some kind of time reset handler before it gets handed off to iMessage.
I've also had Macs online for years without issue.
I guess it only applies to "ephemeral" ports 49152–65535, though I'm not sure what range macOS actually uses. Wikipedia has numbers for Linux and various Windows versions but not macOS: https://en.wikipedia.org/wiki/Ephemeral_port
So does that mean typical desktop usage, like email, web browsing, SSH, etc. would be unaffected? Anyone have any insight on this? I'm not a networking expert myself.
I can't believe the claim that "everything else dies" when that goes directly against observed reality.
Ephemeral ports are used most often for outgoing traffic. Like if you connect to HTTP, the remote port is 80, but the local port could be any TCP port in the ephemeral range.
Yeah, I run a macOS server (on 10.13.6 no less) that regularly has several months of uptime without issue, and I ran my new MacBook Pro for six months since I bought it perfectly fine without rebooting it until a recent update forced me to. I’m not sure what the problem here is.
there may be some “secret sauce” here that combines a certain version of OS, hardware and DHCP. I thought it was an interesting read and thought I would share.
I suppose it is interesting, and I wasn’t complaining about you posting it. I was more a bit puzzled about the somewhat grandiose claims that the headline makes. That’s on the author, not on you.
Because it's not a security issue? It is a bug that would affect long running MacOS machines which is quite low impact.
CVE: Common Vulnerabilities and Exposures
Not a vulnerability or exposure. There's no threat vector here.
Didn't windows XP have a similar bug? Related to the windows uptime counter, iirc.
Windows 9x would crash after 49.7 days.
Windows Vista had a bug where the network stack would crash after 497 days, but if you didn't care about networking the rest of the OS would continue to run.
AI generated crap. Lots of people posting in /r/Apple that they've uptimes many times longer than this without any issue.
I would have to double check my Mac, but my uptime is well over this. Probably around 3 months.
i have a macbook pro at work and before the update a couple days ago the last time i had rebooted it was also at least 3 months ago
Just reading this gave me a flashback to the old Windows 9x issue where, if you left a machine running "too long", it would crash. 😅
Can't recall the number of days, though. 38? 68? 78? Something like that.
That's not a thing.
At 49.7 days a timer overflows. That could cause problems... It doesn't guarantee problems.
That's the one. And fair enough.
Had a couple of users tell me it crashed their PCs, but that was my only reference.
I've encountered this before, on a Mac Pro 5,1. Same thing used to happen to my old Linux machine and I've seen it happen to Win2k waaaaaay back in the day. I recall the whole up-too-long-cant-network thing being quite common at one point. This article feels like a nothing burger.
Lol. Glad to see others using the term "nothing burger".
As I explained elsewhere it's just that. Hype for a new AI model that can't understand the big picture nor the final details and is finding non-existent bugs.
It's a great phrase for things like this lol
Yeah I haven't seen my Mac Pro 6,1 do this in the 2y it's been living in my rack running boinc jobs. Nor my M1 mini at work that goes untouched for months at a time bc I don't need to go there.
Man, the headline.