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Troubleshooting

Here are some common problems you may encounter when developing with LittleHorse, and how to get around them.

ALREADY_EXISTS on TaskDef​

If you get an error like the following:

Exception in thread "main" io.grpc.StatusRuntimeException: ALREADY_EXISTS: TaskDef [my-task] already exists and is immutable.

That means that a my-task TaskDef was already registered in the LittleHorse Kernel with different inputs/outputs. For type safety of live WfRuns and WfSpecs in production, TaskDefs are immutable. To get around this in local development, you can just delete the TaskDef:

lhctl delete taskDef my-task

Nonexistent TaskDef​

If you try to register a WfSpec that uses a TaskDef that hasn't been registered before, you will get an error like the following:

INVALID_ARGUMENT: Thread entrypoint: Node 1-some-task-TASK: Refers to nonexistent TaskDef some-task

This means that you need to register a TaskDef named some-task before you can refer to it in your WfSpecs. You can do that by following this documentation.