gRPC 6 ALREADY_EXISTS vs 9 FAILED_PRECONDITION
Both gRPC 6 (ALREADY_EXISTS) and 9 (FAILED_PRECONDITION) belong to the gRPC Status Codes category. 6 indicates that the entity that a client attempted to create already exists. For example, a file or directory that the RPC was supposed to create already exists. Meanwhile, 9 means 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.
Description
The entity that a client attempted to create already exists. For example, a file or directory that the RPC was supposed to create already exists.
When You See It
A create operation failed because a resource with the same unique identifier or name already exists in the system.
How to Fix
Use a different identifier, or switch to an upsert/update operation if overwriting is acceptable. Check for existing resources before creating.
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.
Key Differences
gRPC 6: The entity that a client attempted to create already exists. For example, a file or directory that the RPC was supposed to create already exists.
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.
You encounter 6 when a create operation failed because a resource with the same unique identifier or name already exists in the system.
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.
When to Use Which
For 6 (ALREADY_EXISTS): Use a different identifier, or switch to an upsert/update operation if overwriting is acceptable. Check for existing resources before creating. 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.