Head 404 dependency issue when trying to write to Blob Storage - azure

Question

I have storage and inside Blob with public access.
but when I am trying to write a document live telemetry shows below Dependency error.
1:21:57 PM | Dependency | 404 | 65
HEAD imagesa| LogLevel=Information | Blob=255274.jpg
Time: 1:21:57 PM
Duration: 65 ms
Outgoing Command: HEAD imagesa
Result code: 404
fileName =imageURL.Substring(imageURL.LastIndexOf(#"/") + 1);
var req = System.Net.WebRequest.Create(imageURL);
using (Stream filestream = req.GetResponse().GetResponseStream())
{
// Get the reference to the block blob from the container
CloudBlockBlob blockBlob = blobContainer.GetBlockBlobReference(fileName);
//create a snapshot
bool existsTask = await blockBlob.ExistsAsync();
if (existsTask == true)
{
// the base blob's metadata is copied to the snapshot.
await blockBlob.CreateSnapshotAsync();
blockBlob.Metadata.Clear();
}
}

Answer 1

I cannot reproduce your issue with the same code in a console app(And if you run your code with some special setting/environment, please point it out).
Please make sure somethings:
1.check if you have set the blob access to public in azure portal, and check your code if use the same blob / container.
2.please use the latest version of WindowsAzure.Storage package, 9.3.3.
And one thing you also need to know: after the code blockBlob.Metadata.Clear(), you need use blockBlob.SetMetadata(). Or it will not clear the metadata.
The code I used:
CloudStorageAccount storageAccount = new CloudStorageAccount(new StorageCredentials("account", "key"), true);
CloudBlobClient cloudBlobClient = storageAccount.CreateCloudBlobClient();
var cloudBlobContainer = cloudBlobClient.GetContainerReference("test-2");
var imageURL = "https://xx.blob.core.windows.net/test-2/sample.JPG";
var fileName = imageURL.Substring(imageURL.LastIndexOf(#"/") + 1);
var req = System.Net.WebRequest.Create(imageURL);
using (Stream filestream = req.GetResponse().GetResponseStream())
{
CloudBlockBlob blockBlob = cloudBlobContainer.GetBlockBlobReference(fileName);
bool existsTask = await blockBlob.ExistsAsync();
if (existsTask == true)
{
await blockBlob.CreateSnapshotAsync();
blockBlob.Metadata.Clear();
blockBlob.SetMetadata(); // add this line of code to ensure the changes to metadata is committed.
}
}
Please let me know if you have more issues.