Many of these error codes are based upon HTTP status codes to help with predictability and familiarity.

1xx codes Informational

100 Continue The request was valid, and another related request is expected.
101 Switching Protocols The request was valid, but can only be served via another protocol. (eg. HTTPS)
102 Informational Message provides information. Experimental/debug only.

2xx codes Success Codes

200 Success The request was successful.
201 Created An object was created successfully. (such as a User)
202 Accepted An object was successfully submitted for processing, but the server doesn’t have information about the status of the request at the moment. (for example, sending of an email)
204 No Content The request was successful, but the server has no data to return.
206 Partial Content Follows The request was valid, and part of the response is being returned. Expect more.

3xx codes Redirection

301 Moved The service URI you have requested has moved permanently. Message contains new location.
303 See Other The service URI is valid, but use the new location for this request only.
304 Not Modified The result of the request has been served from cache.
307 Moved Temporarily Please use the new location for this request only.

4xx codes Client Errors

400 Bad Request The request was malformed and the server could not determine what you were trying to do.
401 Unauthorized You are not authorized for the operation you requested. Please authorize and try again.
404 Not Found The service you requested was not found. Retries will not be successful.
405 Method Not Allowed The method you used to request is not supported, but others are. See message for valid methods (e.g. POST vs GET)
408 Request Timeout Your request timed out during processing. Please wait, then try again later.
409 Conflict The server understood the request, but could not fulfill it due to some resource conflict (e.g. tow people modifying a file). Try again later.
410 Gone Previously, there was a service here, but there is not one any longer. No forwarding information is available.
412 Precondition Failed Some pre-required data for the request was not fulfilled. See message for details.
415 Unsupported Media Type
430 Bad Credentials The credentials given were not valid.
431 Authentication Scheme Not Supported The authentication method you are attempting is not supported by your organization.
432 Protocol Not Allowed Your authentication must be made over a secure channel (e.g. HTTPS).
433 Host Not Allowed You cannot authenticate from your current host using the current method.
434 Service Error Your account is missing information required for authentication (e.g. the shared secret). See message for details.
435 Timestamp Expired The timestamp sent with your authentication request is expired or has been previously used.
436 Unparseable Hash The server could not read the value of the hash parameter that you sent with the request.
437 Unexpected Hash Value The value of the hash parameter you sent does not match what the server was expecting.
438 User Not Found Could not authenticate the user you requested because they could not be found.
439 User Not Created Although the server was expecting to create a user, it could not due to missing information. See message details.
440 Bad Authentication Configuration The configuration setup for this organization is not valid on the server side (e.g. host pattern is invalid)

5xx codes Server Errors

500 Internal Server Error An unexpected error occurred on the server.
501 Not Implemented The server knows about the service, but not how to fulfill it.
503 Service Unavailable The server is currently unavailable. Try again later.
504 Server Timeout The server timed out while talking to an internal resource (such as a database). Try again later.

6xx codes Model Errors

600 Missing Data Soem piece of required data was missing from the request, but the server cannot determine what it is.
601 Missing Data X “X” was missing from the request. See message for what X is.

7xx codes Organization / Limit Errors

700 Not Supported for Organization The request was valid, but not supported for your organization.
701 Limit Exceeded The resource you requested could not be allocated due to limits of your organization (e.g. too many course admins or media file too big).

8xx codes Format Errors

800 Bad Format X The format of X is not valid. See message for what X is.
801 Must Be Numeric X The format of X must be numeric.
802 Invalid Date X The format of X must be a valid date. If a range is required, it is described in the message.
803 Field Too Long X The length of X is too long. See message for valid lengths.
804 Field Too Short X The length of X is too short. See message for valid lengths.
805 May not be empty X Field X may not be empty.

9xx codes Session Errors

901 Session Timed Out