This page describes how gRPC deals with errors, including gRPC's built-in error codes. Example code in different languages can be found here.
### Error model As you'll have seen in our concepts document and examples, when a gRPC call completes successfully the server returns an `OK` status to the client (depending on the language the `OK` status may or may not be directly used in your code). But what happens if the call isn't successful? If an error occurs, gRPC returns one of its error status codes instead, with an optional string error message that provides further details about what happened. Error information is available to gRPC clients in all supported languages. ### Error status codes Errors are raised by gRPC under various circumstances, from network failures to unauthenticated connections, each of which is associated with a particular status code. The following error status codes are supported in all gRPC languages. #### General errors Case | Status code -----|----------- Client application cancelled the request | GRPC_STATUS_CANCELLED Deadline expired before server returned status | GRPC_STATUS_DEADLINE_EXCEEDED Method not found on server | GRPC_STATUS_UNIMPLEMENTED Server shutting down | GRPC_STATUS_UNAVAILABLE Server threw an exception (or did something other than returning a status code to terminate the RPC) | GRPC_STATUS_UNKNOWN