Resource not found

not_found HTTP 404

No such record is visible to this credential.

This is also what you get for a record that exists but belongs to another company — deliberately, since a 403 there would confirm the id exists and let anyone enumerate another tenant's records. So do not read this as proof that an id was never valid.

How to react to this in code

Switch on the code member — not_found — which is stable. Do not parse the type URI: it points here, and where "here" is may change.