The following are frequently asked questions relating to error codes.

Q: Why is my token not working? I keep receiving the following error: '442 Invalid one-time-use token'.

Once a one-time-use token has been used to submit an iframe it cannot be used to load another.

You must request a new one-time-use token prior to submitting each iframe.

Q: Why am I getting a 403 error when I send a request for a one-time-use token? I know my credentials are correct.

To request a one-time-use token you must send a 'POST' request.

Sending a GET request will result in a 403 Forbidden error.

Q: I'm getting a 440 error when I try to specify which merchant to process with. What is wrong?

To troubleshoot this issue, follow the steps below:

1. Make sure there are no typos when you enter the merchant ID.
2. Check that you have access to this merchant.
   You can do this by logging into the Nexio Dashboard.
   If you do not see your desired merchant in the merchant selector dropdown, contact CMS Customer Service
3. Make sure you are sending the variable merchantId as a string and not as an integer.

Q: Why do I keep receiving a 431 'Error from Kount' error while testing?

Please note that fraud checking will be performed by default when saving a card token or running a card transaction.

To solve for unexpected 431 errors while testing your integration, try either of the following solutions:

• Make sure your tests do not include any of the values shown in the Test Kount Verification table.
• Disable Kount verification by including the parameter"processingOptions": { "checkFraud": false } in the body of your request.

(See the Enabling Kount verification tutorial for reference.)

Q: Why am I getting an error saying 'Authorization header requires "Credential" parameter'?

The following is a common AWS error:

`{ "message": "Authorization header requires 'Credential' parameter. Authorization header requires 'Signature' parameter. Authorization header requires 'SignedHeaders' parameter. Authorization header requires existence of either a 'X-Amz-Date' or a 'Date' header. Authorization=Basic Og=="}`

To debug it, please try the following:

• Check that your HTTP method is correct.
  (For example, if the HTTP method is set to PUT when it should be POST you may receive this error)
• Check that your request includes all required path and query parameters
• Check your request for typos in the URL

If you still cannot resolve the error, please contact Integrations Support.