"Purchase Date not Validated"

Hey there DongVu,

Thanks for reaching out to Apple Support Communities. I understand that your AirPods serial number shows ‘Purchase Date not Validated’ when checking the coverage. I’ll be happy to help.

Did you double check to make sure you entered the correct serial number of your AirPods. If you’re having issues reading the serial number, you can use this link to look at it directly on your phone and more:

Find the serial number of your AirPods

Also, make sure you’re entering the serial number at the following site:

Check Your Service and Support Coverage

If that doesn’t help, you may want to reach out to Apple Support so they can look at your AirPods in more detail with you and see why this is happening. You can use this link to reach out:

Contact Apple Support 

Cheers.