Errors

Last updated May 19th, 2022

Error Types

When you make an API call to our endpoints, Mono uses conventional HTTP response codes to indicate the success or failure of the API request. In general, codes in the 2xx range indicate success. Codes in the 4xx range indicate an error that occurred due to the information provided, for example, a required parameter was omitted. Codes in the 5xx range indicate an error with our servers, but these are usually rare.

Below, we have detailed API errors you might using Mono and how to fix them. For widget errors, please get in touch with our support team here.

API Error Codes

Code	Type	What it means
`200`	OK	Everything worked as expected.
`400`	Bad request	The request was not accepted, often due to missing a required parameter.
`401`	Unauthorised	No valid API key provided.
`402`	Request Failed	The request was unacceptable, often due to missing a required parameter.
`403`	Forbidden	The API key doesn’t have permissions to perform the request.
`404`	Not Found	The requested resources doesn’t exist.
`409`	Conflict	The request conflicts with another request (perhaps due to using the same idempotent key).
`429`	Too Many Requests	Too many requests hit the API too quickly. We recommend an exponential backoff of your request.
`500` `502` `503` `504`	Server Errors	Something went wrong on Mono’s end. (These are rare).

Direct Debit Error Codes

Code	Type	What it means
`01`	Direct Debit	Status unknown, please wait for settlement report.
`03`	Direct Debit	Invalid Sender.
`05`	Direct Debit	Do not honor
`06`	Direct Debit	Dormant Account
`07`	Direct Debit	Invalid Account
`08`	Direct Debit	Account Name Mismatch
`09`	Direct Debit	Request processing in progress
`12`	Direct Debit	Invalid transaction
`13`	Direct Debit	Invalid Amount
`14`	Direct Debit	Invalid Batch Number
`15`	Direct Debit	Invalid Session or Record ID
`16`	Direct Debit	Unknown Bank Code
`17`	Direct Debit	Invalid Channel
`18`	Direct Debit	Wrong Method Call
`21`	Direct Debit	No action taken
`25`	Direct Debit	Unable to locate record
`26`	Direct Debit	Duplicate record
`30`	Direct Debit	Format error
`34`	Direct Debit	Suspected fraud
`35`	Direct Debit	Contact sending bank
`51`	Direct Debit	Insufficient funds
`57`	Direct Debit	Transaction not permitted to sender
`58`	Direct Debit	Transaction not permitted on channel
`61`	Direct Debit	Transfer limit Exceeded
`63`	Direct Debit	Security violation
`65`	Direct Debit	Exceeds withdrawal frequency
`68`	Direct Debit	Response received too late
`69`	Direct Debit	Unsuccessful Account/Amount block
`70`	Direct Debit	Unsuccessful Account/Amount unblock
`91`	Direct Debit	Beneficiary Bank not available
`92`	Direct Debit	Routing error
`94`	Direct Debit	Duplicate transaction
`97`	Direct Debit	Timeout waiting for response from destination

Error Handling

While building your Mono integration, we strongly recommend that you keep a log of all API requests you make and the responses you receive. You should keep a log file as part of your application and record the API signature, any API URL parameters, and request body (you may strip the API keys) in JSON. Then, write down the API response code and log the JSON body of the error message if one occurs. When your integration is stable, you can lower the logging level and log only the API name (signature), the response code, and any error messages that may have occurred.

On your Mono dashboard, you can also see the logs of each API call you make. This applies to both successful and failed responses (provided the access key and secret key are correct).

To access your API Logs on the dashboard:

Log in to the Mono dashboard and navigate to Audit Logs > API Logs.
Use the dropdown at the top right to select your Mono App, or filter by Scope (Identity, Statements, etc), Status (failed or successful), and Environment (live or test).
Then, your API call data will be displayed based on the filters you chose.

In addition, the response body will be empty if a standard HTTP error code such as 401 (Not Authorized) or 404 (Not Found) is sufficiently descriptive. The response will also contain an error entity that provides additional information about the incident, including an application error code and a human-readable error description. In other situations, we will utilize the standard response code for client errors (400).