16-Year-Old SQLite Bug Disrupts Tailscale Services

Tailscale experienced significant outages starting in late 2025 due to a long-standing bug in SQLite's write-ahead log (WAL). After a six-month investigation, Tailscale identified the issue with assistance from SQLite maintainers, who developed a new logging tool to trace the problem. The bug, which had been hidden for 16 years, caused repeated database corruption during backup processes. Tailscale relies on SQLite for managing its peer-to-peer networking service, which connects devices in a virtual private mesh network. Despite thorough diagnostics, the team struggled to reproduce the issue due to the absence of reliable triggers. The bug's root cause was linked to SQLite's checkpointing process, which is crucial for database integrity. Tailscale has since resolved the issue and improved its logging capabilities to prevent future occurrences.

Key Points: • A 16-year-old bug in SQLite caused outages for Tailscale users starting in late 2025. • Tailscale collaborated with SQLite maintainers to develop a new tool for diagnosing the issue. • The bug led to repeated database corruption, impacting Tailscale's backup processes.