What causes "unable to list files in %s: %w" in argoproj/argo-workflows?

Check the wrapped error for auth (403) vs network causes.

unable to list files in %s: %w

Error message

unable to list files in %s: %w

What it means

When Delete determines the artifact is a directory prefix, it enumerates all blobs under the prefix with ListObjects before deleting them one by one. If that listing fails, Delete aborts with this error rather than partially deleting the directory.

Source

Thrown at workflow/artifacts/azure/azure.go:379

		WithField("container", artifact.Azure.Container).
		WithField("blob", artifact.Azure.Blob).
		Info(ctx, "Deleting object from Azure Blob Storage")
	containerClient, err := azblobDriver.newAzureContainerClient(ctx)
	if err != nil {
		return fmt.Errorf("unable to create Azure Blob Container client: %w", err)
	}

	isDir, err := azblobDriver.IsDirectory(ctx, artifact)
	if err != nil {
		return fmt.Errorf("unable to test if %s is a directory: %w", artifact.Azure.Blob, err)
	}

	if !isDir {
		return DeleteBlob(ctx, containerClient, artifact.Azure.Blob, true)
	}
	files, err := azblobDriver.ListObjects(ctx, artifact)
	if err != nil {
		return fmt.Errorf("unable to list files in %s: %w", artifact.Azure.Blob, err)
	}
	directoryFile := ""
	for _, file := range files {
		if file == artifact.Azure.Blob {
			directoryFile = file
			continue
		}

		if err := DeleteBlob(ctx, containerClient, file, true); err != nil {
			return err
		}
	}
	if directoryFile != "" {
		return DeleteBlob(ctx, containerClient, directoryFile, true)
	}
	return nil
}

View on GitHub (pinned to 35bff19146)

Solutions

Check the wrapped error for auth (403) vs network causes.
Verify the container exists and credentials have 'Storage Blob Data Reader' role for listing.
Retry the delete; nothing has been deleted yet since listing precedes deletion.
If the prefix is huge and timing out, delete blobs in smaller prefix batches with az CLI or Azure Storage Explorer.
Ensure stable connectivity to the storage endpoint (no aggressive middlebox timeouts).

Defensive patterns

Strategy: retry

Validate before calling

// confirm the directory prefix is listable first
files, err := driver.ListObjects(ctx, artifact)
if err != nil {
    return fmt.Errorf("cannot enumerate prefix %s before delete: %w", artifact.Azure.Blob, err)
}

Try / catch

err := driver.Delete(ctx, artifact)
if err != nil && strings.Contains(err.Error(), "unable to list files") {
    // safe to retry: listing precedes deletion, nothing was deleted
    err = retry.Do(ctx, func() error { return driver.Delete(ctx, artifact) })
}

Prevention

Grant list permission (Storage Blob Data Reader / SAS 'l') on the container.
Keep directory prefixes modest in blob count to avoid long listings.
Handle transient 5xx with exponential backoff at the caller.

When it happens

Trigger: Delete on a directory-style artifact (prefix with blobs beneath it) where the ListBlobsFlat pager fails: auth rejection, network failure, container not found, or the client could not be created.

Common situations: Very large prefixes timing out through proxies; container deleted between IsDirectory and ListObjects; expired SAS token mid-operation; firewall rules blocking the data-plane listing.

Related errors

AI-assisted analysis of argoproj/argo-workflows@35bff19146 (2026-09-03). Data as JSON: /api/errors/28847534daa5dcbc. Report an issue: GitHub.