HDInsight region is not supported. Region code: ln - azure

Question

I receive the error on my output dataset in Azure data factory.
"HDInsight region is not supported. Region code: ln."
It's a little odd as I'm not using HDInsight, it's a pipeline of a custom activity in c# running on Azure batch and Two storage accounts for experimentation purposes.
The datafactory is in North Europe and the rest in UK South.
Does HDInsight perhaps power the data movement?
Reading the FAQ the location of the compute and storage resource can be in separate regions?
Edit:
Here is the activity JSON from inside the pipeline:
"activities": [
{
"type": "DotNetActivity",
"typeProperties": {
"assemblyName": "AzureBatchDemoActivity.dll",
"entryPoint": "AzureBatchDemoActivity.DemoActivity",
"packageLinkedService": "AzureStorageLinkedService",
"packageFile": "/demoactivitycontainer/AzureBatchDemoActivity.zip",
"extendedProperties": {
"SliceStart": "$$Text.Format('{0:yyyyMMddHH-mm}', Time.AddMinutes(SliceStart, 0))"
}
},
"inputs": [
{
"name": "InputDataset"
}
],
"outputs": [
{
"name": "OutputDataset"
}
],
"policy": {
"timeout": "00:30:00",
"concurrency": 2,
"retry": 3
},
"scheduler": {
"frequency": "Hour",
"interval": 1
},
"name": "DemoActivity",
"linkedServiceName": "AzureBatchLinkedService"
}
],

Answer 1

I've been in contact with Azure support in tandem, a very prompt response from them!
It appears to be an incorrect error message when using custom activities along with storage accounts in regions which don't support data movement.
I see re-reading the documentation, there is a subtly:
the service powering the data movement in Data Factory is available
globally in several regions.
-- (supported regions)
I read “globally” incorrectly as meaning everywhere, but I should off read it as in particular regions around the globe.
I assume that even though I'm using a custom activity because there is a source and destination storage accounts involved then it's implicitly considered a "data movement" operation.

Answer 2

I had a similar issue (identical error message) running HDInsightOnDemand. There were no problems with the regions of the storage account.
The problem was that cluster details were not specified in the LinkedService. I guess ADF was confused which cluster to create Linux or Windows, Hadoop or Spark.
Anyway, the solution was to add the following properties in HDInsightLinkedService
"properties": {
"type": "HDInsightOnDemand",
"typeProperties": {
"clusterType": "Hadoop",
"osType": "linux",
"version": "3.5",
...

Answer 3

I had this exact issue and found out it is an Azure bug. 'du' is an internal code for a data center in the North Europe region.
HDInsight or storage of Azure Batch region is not supported. Region code: du.
Two resource groups deployed via the same script to the same region produced one working and one broken Data Factory resource. An Azure support engineer told me it was because a data center in that region was new and had not been white listed yet.
The recommended workaround was to redeploy the environment, and hope the Storage Account would be deployed to a different data center in that region that is white listed.