Experts uncover a 49-day time bomb that is likely slowing down your Mac

If your Mac has been running for weeks without a restart and it feels sluggish, there is a very specific reason for that. Researchers at Photon have uncovered a macOS bug that functions exactly like a ticking time bomb.

After 49 days, 17 hours, 2 minutes, and 47 seconds of continuous uptime, your Mac quietly loses the ability to establish new internet connections. Apps stop working, websites fail to load, and your CPU starts working significantly harder than it should.

So what exactly is happening inside your Mac?

The bug lives in how macOS tracks time for managing network connections. The operating system uses a 32-bit counter, which can hold values up to 4,294,967,295 milliseconds. That ceiling corresponds precisely to 49.7 days of continuous runtime.

Once that number is hit, the counter overflows and rolls back, much like a car odometer flipping from its maximum back to zero. At that point, macOS loses the ability to correctly close finished network connections. Those dead connections start piling up instead of being cleaned up.

Your Mac has around 16,384 connection ports available. Once those fill up with connections that should have been terminated, no new ones can be formed. The CPU then spends increasing effort managing thousands of connections that serve no purpose, which is why the slowdown feels so real.

But why hasn’t your Mac stopped working already?

Well, the strange part is that not everything breaks. Pings still work, and any connections that were already open before the overflow continue functioning normally. It is only new connections that fail, which makes the bug feel inconsistent and hard to diagnose without knowing what to look for.

This class of bug is not new. Windows 95 and Windows 98 famously crashed after 49.7 days for the same underlying reason. Some Linux systems face a related issue on January 19, 2038, when their own 32-bit time counter reaches its limit. macOS is now confirmed to have the same kind of problem.

How to prevent your Mac from slowing down?

The fix right now is straightforward: restart your Mac before the 49-day mark. A reboot resets the counter to zero and gives you another 49.7 days before it happens again.

Photon says it is working on a software-level workaround that would not require a full system restart, but until that arrives, a periodic reboot is your best option.