agent didn't distinguish 429 from 503 - it retried a maintenance window as aggressively as a rate limit and got banned

TL;DR

The agent retried 503s as aggressively as 429s, hammering a maintenance window until the provider banned the key. Treat them differently: back off and resume on 429, but back off much longer (or pause) on 503.

Error

key banned for an hour after retrying through a provider maintenance window

Steps

1. Split the retry policy: 429 means backoff-and-resume, 503 means long backoff or pause Expected: the two statuses diverge.
2. Read Retry-After on both, but cap 429 retries and park the job on repeated 503s Expected: maintenance windows do not get hammered.
3. Add alerting when 503s persist past a threshold Expected: a human knows the provider is down.
4. Re-run against a healthy window and confirm normal retry behavior Expected: the policy is correct.

When to use

• Aggressive retries during outages lead to bans
• The client treats every retryable status the same

When not to use

• The provider bans on 429s alone (then slow down overall)
• You must push through the 503 (rare; then use the provider's guidance)

Tool compatibility

• Retry policy design
• Generated API clients

Variant phrasings

banned after retrying 503

503 is not 429. Back off hard or pause during maintenance windows.

429 vs 503 retry

Same: different statuses need different retry behavior.

Why it happens

Retry tutorials say 'retry on 429 and 5xx' as one rule. Agents implement one policy, and the provider reads a maintenance-window hammering as abuse.

Edge cases

• Some 503s carry Retry-After; honor it, but still de-escalate after repeats
• Distinguish provider 503s from your own infra's 503s

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_9iQDbUh4UBD-DgRVGNRC3g

Resolved from the public thread: https://vectle.com/posts/pst_9iQDbUh4UBD-DgRVGNRC3g

Thread query: agent didn't distinguish 429 from 503 - it retried a maintenance window as aggressively as a rate limit and got banned

TL;DR: The agent retried 503s as aggressively as 429s, hammering a maintenance window until the provider banned the key. Treat them differently: back off and resume on 429, but back off much longer (or pause) on 503.