Bizarre bug in macOS is a 'ticking time bomb' that takes out networking capabilities if a Mac is left on for too long

Date:
Thu, 09 Apr 2026 10:35:00 +0000

Description:
Thinking of leaving your Mac turned on for a couple of months? Beware of a weird macOS bug that'll take out your networking.

FULL STORY ======================================================================Copy link Facebook X Whatsapp Reddit Pinterest Flipboard Threads Email Share this article 0 Join the conversation Follow us Add us as a preferred source on Google Newsletter Tech Radar Get daily insight, inspiration and deals in your inbox Sign up for breaking news, reviews, opinion, top tech deals, and more. Become a Member in Seconds Unlock instant access to exclusive member
features. Contact me with news and offers from other Future brands Receive email from us on behalf of our trusted partners or sponsors By submitting
your information you agree to the Terms & Conditions and Privacy Policy and are aged 16 or over. You are now subscribed Your newsletter sign-up was successful Join the club Get full access to premium articles, exclusive features and a growing list of member rewards. Explore An account already exists for this email address, please log in. Subscribe to our newsletter A very strange bug in macOS has just been found If a Mac is left on for (just over) 49 days, its networking functionality will completely fail The only
cure is a reboot, apparently, but presumably Apple will now be working on an official fix Ever wondered what would happen if you left your Mac on for a couple of months solid? Probably not, but you might be interested to learn that if you did, the networking side of the OS would fall over.

Tom's Hardware reports that Photon wrote a blog post on how it "found a ticking time bomb in macOS TCP networking", an explosive element in the code that "detonates after exactly 49 days." Well, 49 days, 17 hours, two minutes, and 47 seconds to be precise. When macOS has been running continuously for that exact length of time, the operating system will experience an 'integer overflow' that "freezes the internal TCP timestamp clock". Article continues below You may like Workplace devices are way behind on installing the latest updates, with Windows much worse than macOS Windows 11 bug breaks entire desktop for some users luckily there's a fix Time for an upgrade? Report warns outdated operating systems could be the 'unnecessary risk' your
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When that happens, existing TCP network connections won't expire as they should, remaining frozen in place, and eventually, as Photon explains: "Ephemeral ports slowly exhaust, and eventually no new TCP connections can be established at all. ICMP (ping) keeps working. Everything else dies."

In short, networking on the Mac goes completely kaput, and the only cure is
to reboot the machine. Yes, the old 'turn it off and turn it on again' solution.

Photon a company that facilitates building AI agents found this bug on the Macs it uses to monitor Apple's Messages service , and the company successfully reproduced the glitch on two systems. Analysis: Apple following in Microsoft's footsteps (Image credit: Future) Obviously, this isn't a problem that most of you assuming that you own a Mac will have to worry about. No everyday user leaves their machine on for 50 days solid; but in
case you're ever inclined to do so, at least you're now forewarned. This is, of course, more of a glitch that'll hit servers (which do run continuously
for long periods), and one which businesses like Photon need to be aware of. Get daily insight, inspiration and deals in your inbox Sign up for breaking news, reviews, opinion, top tech deals, and more. Contact me with news and offers from other Future brands Receive email from us on behalf of our
trusted partners or sponsors By submitting your information you agree to the Terms & Conditions and Privacy Policy and are aged 16 or over.

The root cause of the issue is, as mentioned, integer overflow. This is where macOS assumes a counter is only going to go up in numerical value, when in fact, it wraps back round to zero after 50 days of ticking up and this is something that's caught out Microsoft in the past, too. Photon reminds us
that Windows 95 suffered a similar 49.7-day crash where the kernel's 32-bit millisecond tick counter overflowed, in this case causing the PC to
completely freeze up.

Apparently Photon is working on a solution to avoid having to reboot in order to fix the Mac, but presumably now that this bug has been brought to Apple 's attention we should see an official fix before long. The best laptops for all budgets Our top picks, based on real-world testing and comparisons

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Link to news story: https://www.techradar.com/computing/mac-os/bizarre-bug-in-macos-is-a-ticking-t ime-bomb-that-takes-out-networking-capabilities-if-a-mac-is-left-on-for-too-lo ng


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