422 Unprocessable Content

The HTTP 422 Unprocessable Content status code indicates that the server understands the request and the request syntax is correct, but it cannot process the request due to errors in the query parameters. This typically occurs when parameter values are invalid, out of range, or violate logical rules.

A 422 response is the correct server behavior when request parameters are syntactically valid but semantically incorrect. The OpenAQ API is properly validating input and preventing invalid queries from executing. This is a client-side parameter validation issue rather than a server malfunction.

How to Resolve

Review the errors array in the response body to identify which specific parameters are invalid and why. Each error will indicate the parameter name, the provided value, and the reason for rejection. Correct the invalid parameters according to the error messages and API documentation requirements for the relevant resource endpoint.

Common issues

Invalid date formats: Providing dates in incorrect format (e.g., datetime_from=2024/01/01 instead of datetime_from=2024-01-01T00:00:00Z)
Date range violations: End date before start date, or date ranges exceeding maximum allowed period
Out of range coordinates: Latitude values outside ±90° or longitude values outside ±180°
Invalid parameter combinations: Using mutually exclusive parameters together or required parameter dependencies not met
Exceeding limits: Requesting page sizes or limits that exceed maximum allowed values
Invalid enum values: Using values not in the accepted list for parameters like units, spatial aggregation types, or measurement methods
Type mismatches: Providing string values where numbers are expected, or vice versa