"Software developer Photon, whose product requires running a bunch of Macs to connect to iMessage, discovered a pretty major bug:

Every Mac has a hidden expiration date. After exactly 49 days, 17 hours, 2 minutes, and 47 seconds of continuous uptime, a 32-bit unsigned integer overflow in Apple’s XNU kernel freezes the internal TCP timestamp clock… ICMP (ping) keeps working. Everything else dies. The only fix most people know is a reboot"

update: "They suggest that the bug may have been around since Catalina, but I’ve had a Mac server running from the Catalina days all the way through Sequoia, with months of uptime, and haven’t seen this problem. I’ve not updated the server to Tahoe yet."

https://mjtsai.com/blog/2026/04/07/tahoe-tcp-overflow-bug/

https://sixcolors.com/link/2026/04/macs-crash-after-49-days-of-uptime/