Firefox 115+ POST retry behavior with network.http.retry.enable_post and Retry-After header
0 reputation · 30 Jan 2020, 04:11 UTC
Firefox 115 introduced the hidden preference network.http.retry.enable_post to allow automatic retries for POST requests that receive a 503 response with a Retry-After header. The feature remains experimental and is not exposed in the UI.
The retry logic verifies that the request body is unchanged between attempts and honors the delay specified by Retry-After. However, the browser cannot guarantee that the server treats the POST as idempotent, so duplicate side-effects remain possible if the endpoint is not designed for safe repetition.
Documentation does not clarify whether the preference also applies to other non-idempotent methods such as PATCH, nor whether the retry count or backoff strategy is configurable beyond the server-supplied header.
What conditions beyond a 503 with Retry-After trigger an automatic POST retry when the preference is enabled? Does the retry mechanism extend to PATCH or other non-idempotent methods? Is there a maximum retry limit or exponential backoff implemented independently of the Retry-After value?
