Describes the cause of the error with structured details.

Example of an error when contacting the "" API when it is not enabled:

{ "reason": "API_DISABLED"
  "domain": ""
  "metadata": {
    "resource": "projects/123",
    "service": ""

This response indicates that the API is not enabled.

Example of an error that is returned when attempting to create a Spanner instance in a region that is out of stock:

{ "reason": "STOCKOUT"
  "domain": "",
  "metadata": {
    "availableRegions": "us-central1,us-east2"
JSON representation
  "reason": string,
  "domain": string,
  "metadata": {
    string: string,


The reason of the error. This is a constant value that identifies the proximate cause of the error. Error reasons are unique within a particular domain of errors. This should be at most 63 characters and match a regular expression of [A-Z][A-Z0-9_]+[A-Z0-9], which represents UPPER_SNAKE_CASE.



The logical grouping to which the "reason" belongs. The error domain is typically the registered service name of the tool or product that generates the error. Example: "". If the error is generated by some common infrastructure, the error domain must be a globally unique value that identifies the infrastructure. For Google API infrastructure, the error domain is "".


map (key: string, value: string)

Additional structured details about this error.

Keys must match /[a-z][a-zA-Z0-9-_]+/ but should ideally be lowerCamelCase. Also they must be limited to 64 characters in length. When identifying the current value of an exceeded limit, the units should be contained in the key, not the value. For example, rather than {"instanceLimit": "100/request"}, should be returned as, {"instanceLimitPerRequest": "100"}, if the client exceeds the number of instances that can be created in a single (batch) request.