There are some errors that should not be retried because they seem permanent:
- 400 Bad Request
- 401 Unauthorized
- 402 Payment Required
- 403 Forbidden
- 405 Method Not Allowed
- 406 Not Acceptable
- 407 Proxy Authentication Required
- 409 Conflict – it depends
- 410 Gone
- 411 Length Required
- 412 Precondition Failed
- 413 Payload Too Large
- 414 URI Too Long
- 415 Unsupported Media Type
- 416 Range Not Satisfiable
- 417 Expectation Failed
- 418 I’m a teapot – not sure about this one
- 421 Misdirected Request
- 422 Unprocessable Entity
- 423 Locked – it depends on how long a resource is locked in average (?)
- 424 Failed Dependency
- 426 Upgrade Required – can the client be upgraded automatically?
- 428 Precondition Required – I don’t thing that the precondition can be
fulfiled the second time without retring from the beginning of the
whole process but it depends - 429 Too Many Requests – it depends but it should not be retried to fast
- 431 Request Header Fields TooLarge
- 451 Unavailable For Legal Reasons
So, most of the 4** Client errors should not be retried.
The 5** Servers errors that should not be retried:
- 500 Internal Server Error – it depends on the cause of the error
- 501 Not Implemented
- 502 Bad Gateway – I saw used for temporary errors so it depends
- 505 HTTP Version Not Supported
- 506 Variant Also Negotiates
- 507 Insufficient Storage
- 508 Loop Detected
- 510 Not Extended
- 511 Network Authentication Required
However, in order to make the microservices more resilient you should use the Circuit breaker pattern and fail fast when the upstream is down.