Skip to main content
When interacting with the Nitro API, you might encounter various HTTP error responses. Here’s a breakdown of the most common error codes and how to resolve them.

​
400 - Bad Request

This error occurs when the request is malformed or contains invalid parameters. Common causes:
  • Missing required fields
  • Invalid query syntax
  • Sending data in the wrong format
How to fix:
  • Double-check your request body or query parameters to ensure all fields are correctly structured.

​
401 - Unauthorized

This error means your request lacks valid authentication credentials. Common causes:
  • Attempting a request with a missing or expired token
  • Attempting a request with an access token in the wrong format.
How to Fix:
  • Verify that your access token is included and valid.
  • Check out the Authentication and Authorization guide if you need go through the process of obtaining credentials and tokens.

​
404 - Not Found

This indicates that the requested resource doesn’t exist. Common causes:
  • Attempting to get or modify a resources that does not exist. For example, trying to add a Document to an Envelope that doesn’t exist.
How to Fix:
  • Check that you’re calling the correct endpoint and using valid resource identifiers.

​
405 - Method Not Allowed

This error means that the resource exists, but it does not accept the HTTP method you used. Common causes:
  • Using the wrong HTTP method for the endpoint.
  • For example, sending a GET request to an endpoint that only supports POST.
How to fix:
  • Check the API reference to confirm which methods are supported for the endpoint, and update your request.

​
408 - Request Timeout

The server timed out before the request could be completed. Common causes:
  • Network problems such as high latency, slow connections, or firewalls can generate a server timeout.
  • Large payloads (for example, document uploads) that take longer than the allowed processing time.
How to Fix:
  • Check your network connection and retry later

​
409 - Conflict

The request could not be completed because of a conflict with the current state of the target resource. The conflict must be resolved before retrying. Nitro-specific causes:
Cause: Uploading a Document to an Envelope that already contains the maximum of 15 Documents.Fix: Remove unused Documents from the Envelope or combine smaller files into a single Document before retrying.
Cause: Attempting to send for signature an Envelope that has already been delivered and is in sent status.Fix: For sending Envelopes, verify the current status and ensure you are not resending an Envelope that has already been delivered.

​
413 - Content too large

This error indicates that the request was valid, but the payload exceeded the maximum size allowed by the system. Nitro-specific causes:
Cause: Attempting to upload a document that is too large.Fix: Ensure that uploaded files are no larger than 20 MB.

​
422 - Unprocessable Entity

This error means the request was well-formed but contains semantic issues the server can’t process. Nitro-specific causes:
Cause: Attempting to add too many documents in an envelopeFix: Make sure your envelope is within the document limits allowed by the Nitro platform (15).

​
500 - Internal Server Error

A generic error indicating something went wrong on our end. Common causes:
  • Server failure
  • Unhandled exception in processing
How to fix:
  • Try your request again later. If the issue persists, contact support with details of your request and error response.
⌘I