Status: 412 : conditional header is not met error - How to ignore ETag checking

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How to ignore ETag checking and fix this error

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Status: 412 : conditional header is not met error - How to ignore ETag checking

Sarah 156

I read blob content from Azure blob storage. The same Blob content is being changed by another program at the same time while it is being downloaded (i.e., new content is written and getting appended to the existing content). I get error in the below stream.Read() line. Which I believe is because of mismatch eTag values as file is both read and writen at the same time. How can I make it ignore checking for ETag.
 
I am actually not setting any "conditional headers" in the request. You could see the error details at the bottom (Status: 412 - The condition specified using HTTP conditional header(s) is not met),  I believe something is happening under the covers that I'm not aware of. 

I tried to set conditional header ETag value as "*" as below. Thinking it would ignore checking for matching ETag values. But this does not work.

Using Azure.Storage.Blobs package.

        originalETag = properties.ETag;
        blobOpenReadOptions = new BlobOpenReadOptions(true)
        {
            Conditions = new BlobRequestConditions()
            {
                IfMatch = new ETag("*") // set as *, thinking this will ignore etag value when I read blob content and not throw error

               //IfMatch = ETag.All
               //IfNotMatch = originalETag
            }
       };

And used the 

    using (var stream = await blob.OpenReadAsync(offset, segmentSize)) 
    {
            await blob.OpenReadAsync(blobOpenReadOptions);
            stream.Position = offset;
            stream.Read(buffer, 0, buffer.Length); // ERROR in this line
            ret.Byte = buffer;
    }


Read() error below:

    Azure.RequestFailedException: The condition specified using HTTP conditional header(s) is not met.
    RequestId:b84cc30f-501e-009f-4596-295240000000
    Time:2023-01-16T10:37:49.1672314Z
    Status: 412 (The condition specified using HTTP conditional header(s) is not met.)
    ErrorCode: ConditionNotMet
    
    Content:
    <?xml version="1.0" encoding="utf-8"?><Error>
    RequestId:b84cc30f-501e-009f-4596-2952400000
    Time:2023-01-16T10:37:49.1672314Z</Message></Error>
    
    Headers:
    Server: Windows-Azure-Blob/1.0,Microsoft-HTTPAPI/2.0
    x-ms-request-id: b84cc30f-501e-009f-4596-29524000000
    x-ms-client-request-id: 70f94258-163a-464c-879f-437d5ac7be7
    x-ms-version: 2021-10-04
    x-ms-error-code: ConditionNotMet
    Date: Mon, 16 Jan 2023 10:37:48 GMT
    Content-Length: 252
    Content-Type: application/xml

       at Azure.Storage.Blobs.BlobRestClient.Download(String snapshot, String versionId, Nullable
       at Azure.Storage.Blobs.Specialized.BlobBaseClient.StartDownloadAsync(HttpRange range, BlobRequestConditions conditions, DownloadTransferValidationOptions validationOptions, Int64 startOffset, Boolean async, CancellationToken cancellationToken)
       at Azure.Storage.Blobs.Specialized.BlobBaseClient.DownloadStreamingInternal(HttpRange range, BlobRequestConditions conditions, DownloadTransferValidationOptions transferValidationOverride, IProgress`1 progressHandler, String operationName, Boolean async, CancellationToken cancellationToken)
       at Azure.Storage.Blobs.Specialized.BlobBaseClient.<>c__DisplayClass97_0.<<OpenReadInternal>b__1>d.MoveNext()
    --- End of stack trace from previous location ---
       at Azure.Storage.LazyLoadingReadOnlyStream`1.DownloadInternal(Boolean async, CancellationToken cancellationToken)
       at Azure.Storage.LazyLoadingReadOnlyStream`1.ReadInternal(Byte[] buffer, Int32 offset, Int32 count, Boolean async, CancellationToken cancellationToken)
       at Azure.Core.Pipeline.TaskExtensions.EnsureCompleted[T](Task`1 task)
       at Azure.Storage.LazyLoadingReadOnlyStream`1.Read(Byte[] buffer, Int32 offset, Int32 count)
       at Project.Server.Models.ItemRepository.GetFile(String fileName, Int64 offset, Int64 blobLengthRemaining, Int64 prevContentLen) in C:\Users\Project\Server\Models\ItemRepository.cs:line 221
       at LogViewer.Server.Controllers.ItemController.GetBlobFile(String fileName, Int64 offset, Int64 blobLengthRemaining, Int64 contentLen) in C:\Users\Project\Server\Controllers\ItemController.cs:line 60
       at lambda_method60(Closure , Object )

.....

Thank you.

Answer 1

Hoekstra Jelle 486

Hi,

Please check the links below.

[https://stackoverflow.com/questions/75155542/how-to-ignore-etag-checking-reading-and-writing-to-blob-content
[https://azure.microsoft.com/cs-cz/blog/managing-concurrency-in-microsoft-azure-storage-2/

Hope this helps

If it does, please accept the answer. (Don't hesitate to ask your questions if you have any)

Sarah 156 Reputation points

2023-01-18T15:52:42.18+00:00

Thank you for the links.
Sarah 156 Reputation points

2023-01-18T15:53:59.9633333+00:00

From the second link: "To explicitly disable the concurrency check, you should set the ETag property of the employee object to “” before you execute the replace operation. customer.ETag = "";

I am trying similar to this in the above code. To disable concurrency check (i.e., if file gets written to, while I am reading it - which throws error - so, setting ETag property to *), I believe this way I wont get 412 error. But does not work so far. Is there any mistake in how I assign *. Would appreciate your input on where I am going wrong.

Please refer this link for detailed code: https://stackoverflow.com/questions/75133380/status-412-the-condition-specified-using-http-conditional-headers-is-not-me. Thank you.

Sarah 156

Retried another way as below: Setting ETag in blobRequestConditions and passing as parameter to OpenReadAsync(). Still same error. May I know if I am missing something.


BlobRequestConditions blobRequestConditions = new BlobRequestConditions
        {
             IfMatch = ETag.All
             //  IfMatch = new ETag("*")
        };

        try
        {
            using (var stream = await blob.OpenReadAsync(offset, segmentSize, blobRequestConditions)) 
 using (var stream = await blob.OpenReadAsync(offset, segmentSize, blobRequestConditions)) 
            {    
                stream.Position = offset;
                stream.Read(buffer, 0, buffer.Length);      // Error in this line
                ret.Byte = buffer;             
            }
        }

Status: 412 : conditional header is not met error - How to ignore ETag checking

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