WhatsApp message failure with Unsupported post request?

If your Whatsapp messages is failing with the error Unsupported post request. Object with ID 'XXXXXXX' does not exist, cannot be loaded due to missing permissions, or does not support this operation.

Invalid or Deleted Object ID:

The ID (XXXX) may not correspond to a valid WhatsApp Business Account (WABA), phone number, or template.

It may have been deleted or never existed.

Permission Issues:

Your access token may not have permission to access the resource.

You might be using a user token instead of a system user or business token.

Missing roles (e.g., WhatsApp Manager) on the business account.

Business Verification Not Complete:

Your business may not have completed Facebook Business Verification.

Or the phone number may not yet be connected to a verified WhatsApp Business account.

Removed Partner:

If you have removed the partner from meta then we do not have the access to the WABA then also this error comes.

Note: If you removed the partner in that we case you need to do the onboarding process again to start the services.