Problem codes

Every refusal is an RFC 9457 problem document with a stable code. Branch on code. title and detail are prose written for a person, and they can change without notice.

Code	Status	Category	Can the identical request succeed later?
authentication_required	401	authentication	no — change something first
credential_expired	401	authentication	no — change something first
credential_revoked	401	authentication	no — change something first
idempotency_key_reused	409	conflict	no — change something first
invalid_request	400	invalid-request	no — change something first
not_found	404	not-found	no — change something first
plan_limit_reached	409	conflict	no — change something first
project_archived	409	conflict	no — change something first
rate_limited	429	rate-limited	yes
revision_conflict	409	conflict	no — change something first
scope_missing	403	authorization	no — change something first
service_unavailable	503	unavailable	yes
state_conflict	409	conflict	no — change something first
test_to_live_escalation	403	authorization	no — change something first
version_conflict	409	conflict	no — change something first

Each quickstart’s step tables say which of these a step can produce and what to do about it.