How do I create an empty file in ADLS Gen2 using ADF’s Web API activity with MSI authentication?

Below is an explanation and a suggested change to your request.

What’s Happening

When using ADLS Gen2, you’re actually working with the hierarchical namespace and the Data Lake (DFS) REST API—not the Blob API. In your request you’re using the Blob-specific header (x-ms-blob-type) and the Blob endpoint (via dfs.core.windows.net). This mismatch causes the service to complain that a required header is missing. Also, when using Managed Identity (“MSI”) authentication, you shouldn’t include a SharedKey Authorization header.

How to Fix It

To create a new empty file in ADLS Gen2:

1. Remove the Blob-specific header:
   The header x-ms-blob-type is only applicable when using the Blob API.

2. Use the Data Lake “Create File” API:
   Instead of using the Put Blob operation, you should use the Data Lake endpoint for file creation. This is done by appending the ?resource=file query string parameter to your URL.

3. Clean up the Authentication:
   Since you’re using System Assigned Managed Identity, remove the SharedKey Authorization header from your request. Let the MSI (Managed Identity) authentication take care of the authorization.

4. Ensure an Empty Body:
   Sending a single whitespace character in the body isn’t interpreted as an empty file. Use an empty body (or omit it) along with Content-Length: 0.

Example Request

Below is an adapted version of your request that follows the above recommendations:

JSONCopied
{
    "method": "PUT",
    "headers": {
        "x-ms-version": "2021-06-08",
        "x-ms-date": "Wed, 29 Jan 2025 14:37:47 GMT",
        "Content-Length": "0"
    },
    "url": "https://sample.dfs.core.windows.net/test-data/csv/archive/test.done?resource=file",
    "body": "",
    "authentication": {
        "type": "MSI",
        "resource": "https://storage.azure.com/"
    }
}

Explanation of Changes

• Removed "x-ms-blob-type" header:
  The file creation operation using ADLS Gen2 does not require (or support) this header.

• Appended Query Parameter:
  The URL now ends with ?resource=file to indicate that you want to create a file in the filesystem rather than perform a blob operation.

• Removed SharedKey Authorization header:
  When you are using Managed Identity (MSI) for authentication, you do not supply a SharedKey token in the header.

• Empty Body:
  By setting "body": "" and "Content-Length": "0", the request is interpreted as creating an empty file.

Using these changes should resolve the missing header issue and properly create an empty file in your ADLS Gen2 account.