Azure Community Forums

Hi everyone,

I'm encountering an issue when trying to upload a large file (around 50GB) to Azure Blob Storage using AzCopy v10 on Windows Server 2019. The upload starts fine, but after a few minutes, it fails with the following error message:

`ERROR: The specified blob does not exist. RequestId:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx Time:2023-10-27T10:15:00Z\n` `Status: 404 The specified blob does not exist.`

I've checked the storage account and container, and they are configured correctly. I'm using SAS tokens for authentication, and they are valid. I've also tried with different files and sizes, but the problem seems to persist with files larger than 20GB.

Has anyone experienced similar issues or can suggest potential causes and solutions?

Hello azure_user_42,

Thanks for reaching out. The 404 error typically indicates that the target resource (blob) was not found at the time of the operation. For large uploads, especially with AzCopy v10, there are a few things to check:

1. **SAS Token Expiration:** Ensure your SAS token's expiry time is significantly longer than your expected upload duration for large files. A short expiry might cause it to invalidate mid-transfer.
2. **Network Stability:** Intermittent network connectivity issues can sometimes lead to partial uploads or corruption, which might be interpreted as a missing blob.
3. **AzCopy Version:** While you're using v10, ensure it's the latest stable build. You can check by running azcopy version.
4. **Parallelism:** AzCopy uses parallel operations. Sometimes, very high parallelism or network limitations can cause race conditions. You might try reducing the --concurrency-per-cpu parameter if you've set it manually.
5. **Blob Type:** Are you uploading to a Block Blob or Append Blob? AzCopy is primarily designed for Block Blobs.
Could you please share the exact AzCopy command you are using (masking any sensitive information like account keys or SAS tokens)? This would help in diagnosing the issue further.

Hi msft_support_eng,

Thanks for the quick response!

1. **SAS Token:** The SAS token has an expiry of 1 year, so that shouldn't be the issue.
2. **Network:** The network connection is stable, and we're not seeing any other connectivity problems.
3. **AzCopy Version:** I'm running azcopy 10.22.0, which I believe is the latest stable.
4. **Parallelism:** I haven't explicitly set the concurrency. It should be using the default settings.
5. **Blob Type:** I'm uploading to a Block Blob.

Here's the command I'm using (with placeholders):

azcopy copy "C:\path\to\largefile.zip" "https://.blob.core.windows.net//largefile.zip?" --recursive=false

I noticed that the upload sometimes completes successfully if I retry multiple times, but it's not consistent.