Errors

Errors are RFC 9457 problem details, sent as application/problem+json. The title names the problem and the detail says what to change:

{
  "title": "Permission required",
  "status": 403,
  "detail": "This needs the EditSettings permission in Acme."
}

Status	Means	What to do
400	The request is invalid. Settings errors are listed per setting under errors.	Fix the request; nothing was changed
401	No token, an expired or revoked one, or a service account token used outside its networks	Sign in again, or check the token and the account’s networks
403	You can reach the device but lack the permission for this call	Ask an admin to grant the permission named in detail
404	No such device or session, or not one you can reach	Check the ID, and the service account’s device scope
409	A conflict, such as someone else’s remote control session (blockingSession)	Show who is connected; retry with takeOver: true if you mean to
429	Too many sign-in attempts from your address	Wait, then retry

A device outside your organisations or your service account’s scope is always 404, never 403, so the API never tells a caller which devices exist elsewhere.

In C#, every error is an OhrApiException. Catch OhrApiException<ProblemDetails> to read the problem, and OhrApiException<HttpValidationProblemDetails> for per-setting errors:

try
{
    await api.UpdateDeviceSettingsAsync(42, patch);
}
catch (OhrApiException<HttpValidationProblemDetails> e)
{
    foreach (var (setting, messages) in e.Result.Errors)
        Console.WriteLine($"{setting}: {string.Join(" ", messages)}");
}
catch (OhrApiException<ProblemDetails> e)
{
    Console.WriteLine($"{e.StatusCode} {e.Result.Title}: {e.Result.Detail}");
}