Ticking time bomb bug in macOS disables network connectivity after 49 days — but there’s a fix

Although you certainly can leave your Mac on for days at a time without any issues, a newly discovered macOS bug will certainly make you think twice about doing so.

As reported by Tom’s Hardware, the AI infrastructure and developer tools startup Photon recently discovered a “ticking time bomb” that affects every Mac. Fortunately, though, this isn’t a security bug that can be exploited by hackers. Instead, it’s the kind of bug that could leave you scratching your head if you use one of the best MacBooks and leave your laptop on for over a month at a time.

According to a blog post from Photon, “every Mac has a hidden expiration date.” No, your Mac won’t become unusable, and you won’t have to upgrade to a new machine. However, “after exactly 49 days, 17 hours, 2 minutes and 47 seconds of continuous uptime,” macOS experiences an “integer overflow” that “freezes the internal TCP timestamp clock.”

But what does this mean for the average Mac user? Well, once your machine has been running for exactly this long, existing TCP network connections won’t expire as they normally should. Essentially, this means that your Mac won’t be able to connect to the internet, which is why many of us get a computer in the first place.

Photon likely let Apple know once it discovered this issue, and the firm is currently working on its own solution. However, there’s an easy fix that won’t require an update or bringing your Mac to an Apple Store.

A simple workaround

If you’re worried about your Mac losing internet connectivity, don’t be. The issue itself stems from integer overflow, where your Mac’s TCP timestamp clock keeps counting until it reaches a max value of 4,294,967,295 seconds or 49.7 days.

To get around this, all you have to do is reboot your Mac before the 49-day mark, and everything will be fine. Just like on one of the best iPhones, you should reboot your Mac every week. To make things easier, you can even schedule your Mac to turn off and on.

Besides fixing this specific macOS bug, a reboot also flushes memory leaks, clears system caches and temp files, cools down the machine and resets peripheral controllers, which can help rectify other odd glitches with Bluetooth and USB-C docks.

Apple isn’t alone here either, as Windows 98 also crashed after 49.7 days of uptime. Likewise, when it comes to running out of digits while counting, this same issue is why we were all so worried about Y2K back in 1999, and it’s also why the year 2038 could lead to similar concerns when Unix is no longer able to measure time for the same reason. But that’s a problem for another day.

I’m sure that Apple is aware of this issue and is taking steps to address it, hopefully in the next big macOS update. In the meantime, though, just remember to give your Mac a reboot every seven days, and you’ll be perfectly fine.

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