Few tips which may help,
Assuming that you have tested your integration ( https://community.clevertap.com/t/how-can-i-test-that-my-clevertap-integration-is-working-for-my-app/49 ) and it is good.
make sure you upload the iOS Development certificate if you're testing in a dev environment and the Production certificate for production. Ensure valid certificate ( https://community.clevertap.com/t/help-my-ios-push-certificate-is-invalid/312 )
Your current error could be caused by the fact that you've uploaded your iOS Production certificate, but chose "APNS Push Mode" as "Development" on the CleverTap dashboard (Settings dashboard ---> Configure push notifications).
Remember, once you upload a certificate, it may take 30-60 minutes for the APNS certificate to update in CleverTap.
Hope this help, If it does not solve the issue email support@clevertap with the campaign link which is resulting in the error for further debugging.