I am making calls to https://developers.google.com/workspace/admin/directory/reference/rest/v1/users/list and searching using the query paramater. It supports many fields including directManagerId.

If I search for directManagerId it gives a 503 error:

{
  "error": {
    "code": 503,
    "message": "Service unavailable. Please try again",
    "errors": [
      {
        "message": "Service unavailable. Please try again",
        "domain": "global",
        "reason": "backendError"
      }
    ]
  }
}

It DOES NOT give the error if I search for other fields.

This gives the error:

curl \
  'https://admin.googleapis.com/admin/directory/v1/users?customer=my_customer&projection=full&query=directManagerId%3D%271234567890%27&viewType=domain_public&key=[YOUR_API_KEY]' \
  --header 'Authorization: Bearer [YOUR_ACCESS_TOKEN]' \
  --header 'Accept: application/json' \
  --compressed

But this does not give an error:

curl \
  'https://admin.googleapis.com/admin/directory/v1/users?customer=my_customer&projection=full&query=directManager%3D%27first.last%40company.com%27&viewType=domain_public&key=[YOUR_API_KEY]' \
  --header 'Authorization: Bearer [YOUR_ACCESS_TOKEN]' \
  --header 'Accept: application/json' \
  --compressed

I can't figure out why. Even if that direct manager Id didn't exist, it would/should return a success with no records found. If it matters for this post, the ID I am giving DOES exist.