I'm working on a process that uses updateFeatures to update features with values from another application which has no awareness of the feature layer's schema. The process works as expected when all of the attributes for the supplied features are valid for the layer's schema, but if any of the attributes are not valid (ex, a single string value is one character longer then the field accepts), the entire updateFeatures call fails with "ArcGISRequestError: 500: Unable to complete operation". The details are "Unable to perform updateFeatures operation." I see similar behavior when submitting the same update through the html form accessed in the REST Services Directory.
Is there a way to validate the feature data for the request and/or configure the feature service so that it's not an all-or-nothing operation, or do we need to implement all field-level validation processing?