HTTP Response Status Codes

Overview

This document provides a comprehensive overview of the HTTP response status codes return by Memfault's API, including their meanings, causes, and recommended client handling.

HTTP Codes

Status Code	Name	Description	Retry Behavior
2xx Success Codes
200	Success	The request was successful. If an action was requested, it was performed synchronously. Data has been returned.	Do not retry
202	Accepted	The request was successful. If an action was requested, it is performed asynchronously.	Do not retry
204	No Content	The request was successful. If an action was requested, it was performed synchronously. There is no data returned.	Do not retry
4xx Error Codes
400	Bad Request	The server can not process the request due to a client error. Please refer to API documentation, or contact us.	Do not retry
401	Unauthorized	The client is not authenticated or has missing credentials in the request.	Do not retry
403	Forbidden	Access to this resource has not been granted. Can also be a result of a quota limit or Memfault plan.	Do not retry
405	Method Not Allowed	The route or method implementation does not exist.	Do not retry
409	Conflict	A duplicate resource exists.	Do not retry
429	Too Many Requests	The rate limit has been hit.	Do not retry. If Retry-After header is present, retry after given seconds.
5xx Success Codes
500	Internal Server Error	This shouldn't happen! If seen, please contact us.	Do not retry
502	Bad Gateway	This shouldn't happen! If seen, please contact us.	Retry with exponential backoff
503	Service Unavailable	Memfault is down for maintenance.	Retry with exponential backoff
504	Gateway Timeout	The request took too long. If seen, please contact us.	Retry with exponential backoff
529	Site is overloaded	Memfault is under excessive load.	Retry honoring the Retry-After response header, if provided. Otherwise retry with exponential backoff

Retries With Exponential Backoff

For HTTP requests identified for retry in the table above, Memfault recommends up to five retry attempts with an exponential backoff of $2^{3n}$ seconds between attempts (where $n$ is the retry number). The example retry strategy follows.

Retry Attempt	Wait Time (seconds)
1	8
2	64
3	512
4	4096
5	32,768

Retry-After HTTP Response Header

5xx and 429 responses can optionally include a Retry-After header. The Retry-After header provides the minimum time the client should wait before retrying the request. The header value can be an integer number of seconds or a date string. For more information, see the MDN Web Docs.