Opencell

Overview

The Opencell - Invoice: Reject Invoice operation allows users to reject one or more invoices associated with a specific billing run in the Opencell system. This is typically used in billing workflows where certain invoices generated during a billing run need to be invalidated or marked as rejected, for example, due to errors, disputes, or failed validations.

Common scenarios:

• A finance team reviews invoices after a billing run and needs to reject those that are incorrect.
• Automated workflows that validate invoice data and programmatically reject those not meeting business rules.
• Integration with customer support processes to handle disputed invoices.

Practical example:
A user runs a monthly billing process, but some invoices contain incorrect charges. Using this node, they can select the relevant billing run and specify which invoices to reject, ensuring only valid invoices proceed to further processing or payment.

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Properties

Name	Type	Meaning
Authentication	options	Selects the authentication method for connecting to Opencell (Basic Authentication or OAuth2).
Billing Run ID	number	The unique identifier of the billing run containing the invoices to be rejected.
Invoices	fixedCollection	A collection where each entry specifies an Invoice ID to be rejected.
Body Content Type	hidden	Internal property; always set to "multipart-form-data" (not user-facing).

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Output

• The output is a JSON object returned from the Opencell API after attempting to reject the specified invoices.
• The structure of the output depends on the Opencell API's response for the rejectInvoice endpoint. Typically, it may include:
  • Status of the rejection operation
  • Details about each invoice processed (e.g., success/failure, error messages)
  • Any additional metadata provided by Opencell

Example output (structure may vary):

{
  "status": "SUCCESS",
  "rejectedInvoices": [
    {
      "invoiceId": 12345,
      "result": "REJECTED"
    },
    {
      "invoiceId": 67890,
      "result": "ALREADY_REJECTED"
    }
  ]
}

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Dependencies

• External Service: Requires access to an Opencell instance with API enabled.
• Authentication: Needs either Basic Authentication credentials or OAuth2 credentials configured in n8n.
• n8n Configuration: Credentials must be set up under the names opencellApi (for Basic Auth) or opencellOAuth2Api (for OAuth2).

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Troubleshooting

Common issues:

• Invalid Billing Run ID: If the provided Billing Run ID does not exist, the API will return an error.
• Invoice IDs not found: If any specified Invoice ID does not belong to the given billing run or does not exist, the operation may fail or partially succeed.
• Authentication errors: Incorrect credentials or missing permissions will result in authentication failures.
• API connectivity: Network issues or incorrect Opencell API URLs can cause connection errors.

Typical error messages and resolutions:

• "Username/password error. Error code : 401"
  → Check your Basic Auth credentials.
• "Host error. Error code : ENOTFOUND"
  → Verify the Opencell API URL and network connectivity.
• "Invalid credentials (unknown error)"
  → Double-check credential configuration in n8n.
• "Unable to get custom fields. Server response: ..."
  → Not directly related to this operation, but indicates misconfiguration if encountered.

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Links and References

• Opencell Documentation
• n8n Docs: Credentials
• n8n Docs: Custom Nodes