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HTTP Status Codes Error 503: Service Unavailable

Critical↻ Retryable · exponential backoffHTTP 503 Service UnavailableAPI Gateway

TL;DR · 10-second read

The server or load balancer has no healthy capacity (overload, maintenance, zero healthy targets). Retry after Retry-After; check health checks and autoscaling.

Identify: does your log match?

What you see · exact log / response

HTTP/1.1 503 Service Unavailable
Retry-After: 120
Content-Type: text/plain

upstream connect error or disconnect/reset before headers. reset reason: connection failure

Fix

Being written

Copy-paste fixes for 503 are in the enrichment queue

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Related errors

Last verified 2026-10-11 · Source: IANA HTTP Status Code Registry (RFC 9110) · Official docs ↗ · ~49,500 searches/mo