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Nylas uses conventional HTTP response codes to indicate the success or failure of an API request.

Status Codes

Status Code Description
200 OK Everything worked as expected.
202 Not Ready The request was valid, but the resource wasn't ready. Retry the request with an exponential backoff.
400 Bad Request The request is malformed or missing a required parameter.
401 Unauthorized Could not verify access credential. No valid API key or access_token was provided.
402 Request Failed or Payment Required The request parameters were valid, but the request failed. Or, a credit card must be added to your organization.
403 Forbidden The request includes authentication errors, blocked developer applications, and cancelled accounts.
404 Not Found The requested item doesn't exist.
405 Method Not Allowed You tried to access a resource with an invalid method.
410 Gone The requested resource has been removed from our servers.
413 Request Entity Too Large Transmitted data value exceeds capacity limit for Send and Files requests.
418 I'm a teapot. 💁
422 Sending Error This response returned during the sending process.
429 Too Many Requests Slow down! If you legitimately require this many requests, please contact support.
500, 502, 503 Server errors An error occurred in the Nylas server. If this persists, see our status page or contact support.
504 Server error The action timed out making an external request. Please try again.

Empty PUT Request

Sending a PUT request with an empty body will result in a 400 error Empty request body.

View a full list of possible codes on the List of HTTP Status Codes on Wikipedia or the HTTP Status Codes database.

Error bodies include a JSON object with a standard set of attributes, including an error type and a human-readable message string. These are designed to make debugging easier and allow for different handling of scenarios, that produce the same HTTP status code.

Error Type Details
api_error A general API error occurred.
invalid_request_error The request has an invalid format.
provider_error An error with the underlying account's provider has occurred.

400 Bad Request Example

Response provides JSON object information.

"message": "Invalid datetime value z for start_time",
"type": "invalid_request_error"

Mail Sync Events

View the logs for Mail Sync status in the Nylas Dashboard under the Mailsync tab.

Events Description
Failed to parse message. Unable to parse message due to one or more of the following.
  • No message received date
  • Error parsing RAW message
  • Processing synced messages missing namespace_id or body_string
  • Message body too long
  • Recipient field too long
Couldn't parse API error response. JSON object formatting incorrect or incomprehensible.
Invalid credentails response to sync request; aborting sync. User must reauthenticate. Settings have changed for Credentials or Server Settings. Resolve the issue using the Invalid Credentials guide.
Max EAS failures reached, terminating folder sync. Deactivates sync for the account due to folder hierarchy sync failure.
Object not found, resyncing folder hierarchy. Client fetch or change operation no longer has valid server value for CollectionID (EAS folder ID) or ServerID. Examples include deleted items.
Encountered batch-level sync error; not persisting data for affected folder. Continues to next batch because of an error while parsing data.
Resynced more than MAX_UID_RESYNCS in a row. Stopping sync. With IMAP servers that issue continuous UIVALIDITY errors, Nylas tracks consecutive instances and abandons sync at MAX_UID_RESYNCS value.
Error authenticating; stopping sync. Provider gives an authetnication error. Applies to Gmail and Microsoft.
Folder state loading failed due to missing folder. Unable to find folder for folder_id indicating a deleted folder for engine.
Maxed out retries failing to send webhook notification email. Webhook notification delivery attempted the maximum number of times and failed.
Error sending webhook notification email. Confirms failed webhook notification delivery after maximum number of attempts.