A newly discovered macOS networking bug means you should restart your Mac before it reaches 49 days of uptime. If you do not, your system can suddenly lose the ability to make new network connections, effectively breaking internet access across apps and services.
The issue was identified by Photon after repeated failures across its Mac based infrastructure. What made the bug difficult to trace is that affected machines still appeared online. Existing connections continued to work, but any new request simply failed, creating a confusing and inconsistent networking state.
At the center of this macOS networking bug is how the XNU kernel tracks time. macOS uses a 32 bit counter to measure uptime, which maxes out at 4,294,967,295 milliseconds. That limit translates to 49 days, 17 hours, 2 minutes, and 47 seconds. Once reached, the counter resets back to zero.
This reset breaks TCP connection handling. macOS relies on timestamps to determine when inactive connections should be cleared. When the timer overflows, the system miscalculates connection age and stops cleaning them up entirely. Old connections remain open indefinitely, consuming resources that are needed for new ones.
As those unused connections pile up, the system eventually runs out of available ports. At that point, no new TCP connections can be created, and networking across the Mac grinds to a halt. This is why the macOS networking bug 49 days limit is so critical, especially for systems that rely on consistent uptime.
The macOS networking bug affects all Macs, from everyday laptops to high performance machines like Mac Studio and Mac mini setups used in development pipelines. Most users will never notice it because routine updates and restarts usually happen well before the limit is reached.
However, the risk is real for long running systems. Mac servers, CI CD runners, remote Mac mini clusters, and workstations handling extended renders or simulations are the most vulnerable. In these cases, uptime can easily exceed 49 days, making the bug far more likely to trigger.
Right now, there is no software patch available. The only reliable workaround is to restart your Mac regularly. Doing so resets the system timer and clears out all TCP connections, preventing the overflow condition from ever occurring.
If you rely on your Mac for continuous workloads, it is worth setting a restart schedule well under the 49 day limit. Even a weekly restart is enough to completely avoid the issue and maintain stable networking performance.
(via Photon)
