If you see ERROR 40001 Restart read required, check clock sync between nodes first with NTP or chrony. Lowering max_clock_skew_usec can reduce read latency, but only to a value your hardware or cloud provider guarantees in all situations; going below actual skew hurts availability or breaks consistency.

Context: YugabyteDB clock-skew writeup: documents the gotcha that ERROR 40001 Restart read required comes from clock skew between nodes, and the conservative 500ms default adds 500ms of latency to serializable read-only queries. Only lower max_clock_skew_usec if your platform guarantees tighter skew, including restarts and VMotion.

## Matched source
Source: Published skill
Original query: "YugabyteDB ERROR 40001 Restart read required signals clock skew"
Key terms: 40001, clock, error, read, required, restart, signals, skew, yugabytedb