Version conflicts, concurrent writes, and precondition failures.
Last reviewed: February 13, 2026|16 mapped errors|Page 2 of 2
Conflict errors occur when current resource state no longer matches caller assumptions, commonly under concurrent writes or stale version tokens.
Provider-specific error pages mapped to this category (16 total). Showing 16-16.
Compare Guide
Choose 412 when If-Match or If-Unmodified-Since checks fail; choose 409 for state conflicts without failed precondition headers during concurrent updates.
Playbook
Use this playbook to separate true write conflicts from stale precondition failures, then apply safe re-fetch, optimistic-lock, and retry choices.
409 indicates a state conflict during processing, while 412 indicates a declared precondition (for example If-Match) evaluated to false.
Retries increase concurrent write pressure and can replay stale versions. Without fresh reads and merge logic, conflict rates rise quickly.
Use optimistic concurrency with version tokens and idempotency keys, then isolate high-contention keys with targeted partitioning strategies.