AWS IoT JITP - ResourceRegistrationFailureException

Based on the available documentation, ResourceRegistrationFailureException indicates that the resource registration failed during the provisioning process, with an HTTP Status Code of 400. Unfortunately, the standard error response typically only includes a general message for the exception without more granular details about which specific resource caused the failure.

Regarding your specific situation with JITP (Just-in-Time Provisioning), the behavior you're describing relates to how AWS IoT handles provisioning when Things already exist with multiple certificates or Thing Group memberships. The OverrideSettings with "ThingGroups": "REPLACE" and "ThingPrincipalType": "EXCLUSIVE_THING" are designed to handle these scenarios explicitly.

When using JITP, the provisioning template defines how resources should be created or updated. Without explicit override settings, the system may encounter conflicts when attempting to provision a device that already has existing resources, particularly when dealing with multiple certificates or Thing Group associations. The "EXCLUSIVE_THING" setting ensures that the certificate being provisioned has an exclusive relationship with the Thing, while "REPLACE" for Thing Groups explicitly handles the group membership updates.

To obtain more detailed information about provisioning failures, I recommend:

1. Checking your AWS IoT Core logs in CloudWatch Logs, which may contain additional context about the failure
2. Reviewing the IoT Rules Engine logs if you have any rules triggered by the JITP process
3. Examining the certificate registration status and any associated error details in the AWS IoT console

For questions about specific backend changes or service updates that may have occurred during a particular timeframe, you can add correspondence to your existing case through the AWS Support Center at https://console.aws.amazon.com/support/ where the support team can investigate service-level changes and provide more detailed troubleshooting assistance for your specific account and configuration.
Sources
RegisterThing - AWS IoT
Provisioning identity in AWS IoT Core for device connections - Device Manufacturing and Provisioning with X.509 Certificates in AWS IoT Core
Provisioning devices that have device certificates - AWS IoT Core

It may requires explicit handling of overlapping resources (Thing Groups, multiple certificates) via OverrideSettings and ThingPrincipalType.

https://docs.aws.amazon.com/iot/latest/developerguide/jit-provisioning.html

https://repost.aws/questions/QUvzNVEaoTQw6Dt21eRKBbOA/resourceregistrationfailureexception-when-calling-the-registerthing-operation