Resource not found. The requested resource doesn't exist.
For example, a CA set is not found because it's non-existent. That is, the CA set with caSetId in URL doesn't exist in database under your account.

Content-Type: application/problem+json;charset=UTF-8
    "caSetIdentifier": "caSetId",
    "caSetIdentifierValue": "4",
    "detail": "Cannot get CA set activations as the CA set with caSetId 4 is not found.",
    "instance": "/tcm-api/error-types/ca-set-not-found?traceId=-7657402781766012723",
    "status": 404,
    "title": "CA set is not found.",
    "type": "/tcm-api/error-types/ca-set-not-found"