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

If your Mac has been running for an extended period without a restart and is starting to feel sluggish, there may be a specific reason behind it. Researchers at Photon have identified a macOS bug that acts like a ticking time bomb.

After approximately 49 days, 17 hours, 2 minutes, and 47 seconds of continuous uptime, your Mac may lose the ability to establish new internet connections. This can lead to apps malfunctioning, websites failing to load, and an increase in CPU usage.

What is causing this issue on your Mac?

The bug resides in how macOS handles time for managing network connections. The system utilizes a 32-bit counter, capable of storing values up to 4,294,967,295 milliseconds. This equates precisely to 49.7 days of continuous operation.

Once this threshold is reached, the counter resets back to zero, similar to a car’s odometer rolling over. At this stage, macOS struggles to correctly close terminated network connections, leading to a buildup of redundant connections that are not being cleared.

Your Mac typically has around 16,384 connection ports available. When these ports become filled with inactive connections, new connections cannot be established. Consequently, the CPU expends more resources managing these unnecessary connections, resulting in the noticeable slowdown.

Why hasn’t your Mac completely stopped functioning yet?

Surprisingly, not all functions on your Mac come to a halt. Pings continue to work, and existing connections remain operational post-overflow. It’s the initiation of new connections that experiences failures, making the bug challenging to detect without prior knowledge.

This type of bug is not a new phenomenon. Windows 95 and Windows 98 encountered similar issues after 49.7 days due to the same underlying cause. Some Linux systems may face a related problem on January 19, 2038, when their 32-bit time counter reaches its limit. macOS now joins the list of systems affected by this issue.

How can you prevent your Mac from slowing down?

The current solution is simple: restart your Mac before reaching the 49-day mark. A reboot resets the counter, providing another 49.7 days before the issue recurs.

Photon is actively developing a software-based workaround that eliminates the need for a full system restart. However, until this solution is available, periodic reboots remain the most effective strategy.