HTTP 422 Unprocessable Entity — Validation Error Handling

Overview

HTTP 422 Unprocessable Entity means the server understands the request format but cannot process the contained instructions due to semantic errors.

Key Details

• 422 indicates the request is syntactically correct but semantically invalid
• Originally from WebDAV (RFC 4918) but widely adopted by REST APIs
• Common for form validation errors — fields are present but values are invalid
• Different from 400 Bad Request which means the syntax itself is wrong
• Response body should contain specific validation error details

Common Causes

• Form field values failing server-side validation (invalid email, password too short)
• JSON structure is valid but business rules reject the data
• Required fields present but with invalid or out-of-range values
• Data type correct but value violates constraints (negative age, future birth date)

Steps

1. 1Read the response body for specific field-level validation errors
2. 2Fix the invalid field values according to the error messages
3. 3Check API documentation for field format requirements and constraints
4. 4Add client-side validation to catch errors before sending to the server
5. 5Log 422 responses to identify common user input mistakes

Tags

More in 4xx Client Error

Frequently Asked Questions