gRPC 9 FAILED_PRECONDITION vs 12 UNIMPLEMENTED
Both gRPC 9 (FAILED_PRECONDITION) and 12 (UNIMPLEMENTED) belong to the gRPC Status Codes category. 9 indicates that the operation was rejected because the system is not in a state required for the operation's execution. For example, deleting a non-empty directory. Meanwhile, 12 means that the operation is not implemented or is not supported/enabled in this service.
Description
The operation was rejected because the system is not in a state required for the operation's execution. For example, deleting a non-empty directory.
When You See It
The request is valid on its own, but the system's current state doesn't allow it — like trying to delete a non-empty directory or update a resource that has been modified concurrently.
How to Fix
Bring the system into the required state before retrying. For example, empty the directory first, or re-read the resource to get the latest version before updating.
Description
The operation is not implemented or is not supported/enabled in this service.
When You See It
The client called an RPC method that the server does not implement. This often happens when the client uses a newer proto definition than the server supports.
How to Fix
Verify the server version supports the method you're calling. Update the server to implement the missing method, or use an alternative endpoint.
Key Differences
gRPC 9: The operation was rejected because the system is not in a state required for the operation's execution. For example, deleting a non-empty directory.
gRPC 12: The operation is not implemented or is not supported/enabled in this service.
You encounter 9 when the request is valid on its own, but the system's current state doesn't allow it — like trying to delete a non-empty directory or update a resource that has been modified concurrently.
You encounter 12 when the client called an RPC method that the server does not implement. This often happens when the client uses a newer proto definition than the server supports.
When to Use Which
For 9 (FAILED_PRECONDITION): Bring the system into the required state before retrying. For example, empty the directory first, or re-read the resource to get the latest version before updating. For 12 (UNIMPLEMENTED): Verify the server version supports the method you're calling. Update the server to implement the missing method, or use an alternative endpoint.