Executing Power Query activity returns Internal Server Error
I'm getting an InternalServerError from a Power Query activity and I can't see why! The Power Query editor reports no errors (either PQ or Spark-related). The error message isn't super-informative:
I get this error using the AutoResolveIntegrationRuntime, both in debug mode and when published. I've also tried using a fixed-region Azure IR in UK South but get the same result.
The pipeline contains a single Power Query activity. The invoked Power Query has a number of steps, but none of them reports an error in the PQ editor. I'm aware that not all M functions are supported in ADF (yet), but I don't get any message to suggest that's the problem here. I'd welcome some advice! Many thanks