External table is not accessible because content of directory cannot be listed

Question

I am getting this error message whenever I try to run a SQL query in Synapse, even though I have Storage Blob Data Contributor & Storage Blob Data Reader access.

Any ideas on what else is causing this error?

Answer 1

you can try

Check the storage account and container permissions: Verify that you have the necessary permissions at the storage account and container level. Ensure that you have both "Storage Blob Data Contributor" and "Storage Blob Data Reader" roles assigned to your account or the service principal you're using to access the data.

Validate the connection string: Double-check the connection string used in your external table definition. Ensure that it specifies the correct storage account name, container name, and credentials. A small mistake in the connection string can lead to this error.

Verify the path and file format: Confirm that the path specified in the external table definition is correct and matches the actual location of the data files in the storage container. Additionally, ensure that the file format specified in the external table matches the format of the files in the container.

Check the firewall and virtual network settings: If you have enabled firewall rules or virtual network service endpoints on your storage account, ensure that the necessary IP ranges or virtual network settings are properly configured to allow access to the storage account from your Synapse Analytics workspace.

Validate the data format and file structure: Ensure that the files in the storage container are in the expected format and structure defined in your external table. Any mismatch between the file structure and the table definition can cause issues when accessing the data.

Confirm the data location: If the storage account is in a different Azure region or on-premises, ensure that there are no network connectivity issues or latency that might be causing the error.

Check for file or directory-level ACLs: If you have specified file or directory-level access control lists (ACLs) for the files in your storage container, verify that the necessary permissions are granted to your account or the service principal used to access the data.

By investigating these potential causes and following the troubleshooting steps, you should be able to identify the reason behind the error message and resolve the issue with accessing the external table in Azure Synapse Analytics.

Answer 2

Hi Jameel,

Thank you for posting query in Microsoft Q&A Platform.

Similar issue discussed and solved here. Kindly check it.

Hope this helps. Please let me know how it goes or any further queries.

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Please consider hitting Accept Answer button. Accepted answers help community as well.

Answer 3

I had the same problem - directory could not be listed despite the Managed ID I was using having Storage Blob Data Reader on the Storage Account.

I had to add the user to ACL's in ADLS then it worked.

However, I am very confused because my understanding is that ACL's aren't needed if the user has RBAC permissions -(which it did).