Skip to main content
This page covers the most common issues you’ll encounter when calling the knowledge API, with error responses and steps to resolve them.

Invalid CCN format

The CCN must be exactly 6 digits. Letters, short strings, or non-numeric characters are rejected. Request:
Error response:
Solution: Ensure the CCN is exactly 6 numeric digits. Leading zeros matter — 050001 (California) is not the same as 50001. Pad with zeros if needed.

Unknown state code in CCN

The first two digits of the CCN must be a valid CMS state code (01-53). Error response:
Solution: Verify the CCN against the provider’s Medicare enrollment. State codes are CMS-specific and differ from FIPS or postal codes. For example, state code 17 is Kansas, not Illinois.
Valid state codes range from 01 (Alabama) to 53 (Wyoming). Puerto Rico is 40 and the Virgin Islands is 48.

Missing CPT for L5/L6

Layers L5 (Service Group) and L6 (Service) require a CPT code. If you request these layers without one, L5 defaults to E/M and L6 returns a skip notice. Request:
Response:
Solution: Include the cpt query parameter:

CPT code not in RVU table

If the CPT code exists but hasn’t been loaded into the RVU data, L6 returns a note rather than payment data. Response:
Solution: This typically means the CMS MPFS data hasn’t been loaded for the current year. Contact your administrator to run the data loader, or verify the code is a valid CPT/HCPCS code that is payable under the MPFS.

Payer not recognized

L4 maps payer names through an alias system. Unrecognized payers fall back to generic commercial rules. Request:
Response:
This is not an error — unrecognized payers receive the generic commercial profile. Use recognized names for specific rules:

Invalid layer name

When requesting a specific layer, use the canonical names. Request:
Error response:
Solution: Use one of the valid layer identifiers:

Authentication errors

All knowledge endpoints require a valid API key in the X-API-Key header. Missing or invalid keys return 401 Unauthorized. Expired keys or keys without the knowledge scope return 403 Forbidden.
Solution: Verify your API key is active and has the knowledge scope. Generate a new key from the admin dashboard if needed.