Understanding "Invalid mi code under Meta tag" Error

The error "Invalid mi code under Meta tag" is a technical issue encountered primarily in applications integrating with the UIDAI (Unique Identification Authority of India) authentication APIs—especially during biometric authentication. This error is commonly associated with Aadhaar-based authentication systems and registered biometric devices.

What Does the Error Mean?

The error code 524 specifically refers to:

"Invalid 'mi' code under Meta tag"

• mi stands for Model Id – a mandatory attribute in the <Meta> tag of the authentication request XML when performing biometric-based authentication using registered devices.
• The Model Id identifies the specific model of the biometric device being used.

Why Does This Error Occur?

Several reasons may trigger the "Invalid mi code under Meta tag" error:

• Incorrect or Missing Model Id: The mi attribute is missing or does not match any certified biometric device model registered with UIDAI.
• Non-compliance with UIDAI Specifications: Outdated or invalid values used in the mi field.
• Device Registration Issues: The biometric device may not be properly registered or its model info not fetched from the RD (Registered Device) service.
• Software or Firmware Updates: Updates may change the Model Id or require reconfiguration.

How to Resolve the Error

To fix the "Invalid mi code under Meta tag" error, follow these steps:

1. Ensure Correct Model Id Fetch the correct Model Id from the RD service and include it in the mi attribute of the <Meta> tag.

2. Update Device Certificates After vendor updates or certificate changes, verify that the correct Model Id and certificates are used.

3. Follow UIDAI API Specifications Use the latest UIDAI API documentation and ensure all attributes, including mi, are valid.

4. Device Troubleshooting

   • Clear application cache
   • Reconnect the biometric device
   • Restart the application

5. Raise a Support Ticket If issues persist, contact support with detailed information (device ID, user ID, etc.).

Best Practices for Using Custom Meta Tags

While the mi code issue is specific to UIDAI, general best practices for HTML meta tags include:

• Validation Concerns: Unregistered/custom meta names can cause validation errors (e.g., W3C).
• Alternatives: Use data-* attributes, HTML comments, or microdata for custom metadata.
• Security: Avoid exposing sensitive info through public-facing HTML tags.

Summary Table: Common UIDAI Meta Tag Errors

Conclusion

The "Invalid mi code under Meta tag" error signifies an issue with the Model Id (mi) in Aadhaar biometric authentication requests. Resolving it requires:

• Ensuring correct device information
• Compliance with UIDAI specifications
• Regular updates of device certificates

For unresolved issues, consult technical support or your device vendor.