# Status Response Codes

The following status codes can be returned in gRPC responses. This is applicable
to all versions of gRPC documented on this site.

| Code | Status | Notes |
|---|---|---|
| 0 | `OK` | Return on `Success` |
| 1 | `CANCELLED` | The operation was cancelled, typically by the caller. |
| 2 | `UNKNOWN` | For example, this error may be returned when a Status value received from another address space belongs to an error-space that isn't known in this address space. Also errors raised by APIs that don't return enough error information may be converted to this error. |
| 3 | `INVALID_ARGUMENT` | The client specified an invalid argument. |
| 4 | `DEADLINE_EXCEEDED` | The deadline expired before the operation was complete. For operations that change the state of the system, this error may be returned even if the operation is completed successfully. For example, a successful response from a server which was delayed long enough for the deadline to expire. |
| 5 | `NOT_FOUND` | Some requested entity wasn't found. |
| 6 | `ALREADY_EXISTS` | The entity that a client attempted to create already exists. |
| 7 | `PERMISSION_DENIED` | The caller doesn't have permission to execute the specified operation. Don't use `PERMISSION_DENIED` for rejections caused by exhausting some resource; use `RESOURCE_EXHAUSTED` instead for those errors. Don't use `PERMISSION_DENIED` if the caller can't be identified (use `UNAUTHENTICATED` instead for those errors). To receive a `PERMISSION_DENIED` error code doesn't imply the request is valid or the requested entity exists or satisfies other pre-conditions. |
| 8 | `RESOURCE_EXHAUSTED` | Some resource has been exhausted, perhaps a per-user quota, or perhaps the entire file system is out of space. |
| 9 | `FAILED_PRECONDITION` | The operation was rejected because the system is not in a state required for the operation's execution. For example, the directory to be deleted is non-empty or an rmdir operation is applied to a non-directory. |
| 10 | `ABORTED` | The operation was aborted, typically due to a concurrency issue such as a sequencer check failure or transaction abort. |
| 11 | `OUT_OF_RANGE` | The operation was attempted past the valid range. |
| 12 | `UNIMPLEMENTED` | The operation isn't implemented or isn't supported/enabled in this service. |
| 13 | `INTERNAL` | Internal errors. This means that some invariants expected by the underlying system have been broken. This error code is reserved for serious errors. |
| 14 | `UNAVAILABLE` | The service is currently unavailable. This is most likely a transient condition that can be corrected if retried with a backoff. |
| 15 | `DATA_LOSS` | Unrecoverable data loss or corruption. |
| 16 | `UNAUTHENTICATED` | The request doesn't have valid authentication credentials for the operation. |

Sometimes multiple error codes may apply. Services should return
the most specific error code that applies. For example, prefer
`OUT_OF_RANGE` over `FAILED_PRECONDITION` if both codes apply.
Similarly, prefer `NOT_FOUND` or `ALREADY_EXISTS` over `FAILED_PRECONDITION`.

### FAILED_PRECONDITION vs. ABORTED vs. UNAVAILABLE

The following is a litmus test that may help you decide between
`FAILED_PRECONDITION`, `ABORTED`, and `UNAVAILABLE`:

- Use `UNAVAILABLE` if the client can retry just the failing call.
- Use `ABORTED` if the client should retry at a higher-level, such as when a client-specified test-and-set fails which indicates that the client should restart a read-modify-write sequence.
- Use `FAILED_PRECONDITION` if the client should not retry until the system state has been explicitly fixed. For example, if an "rmdir" fails because the directory is non-empty, it is best to return `FAILED_PRECONDITION` because the client should not retry unless the files are deleted from the directory.

### INVALID_ARGUMENT vs. FAILED_PRECONDITION vs. OUT_OF_RANGE

The following is a litmus test that may help you decide between
`INVALID_ARGUMENT`, `FAILED_PRECONDITION`, and `OUT_OF_RANGE`:

- Use `INVALID_ARGUMENT` if the arguments are problematic regardless of the state of the system. For example: a malformed URL
- Use `OUT_OF_RANGE` if a value is out of range due to the state of the system. For example, the start_date is before `start_date_restrict`.
- Use `FAILED_PRECONDITION` if the value is invalid due to the state of the system, but isn't an `OUT_OF_RANGE` value.