New azure function (with .net 8) isolated model (Blob trigger),, azure function v4 is showing error 'WorkerExtensions.csproj : error NU1102: Unable to find package Microsoft.Azure.WebJobs.Extensions.Storage.Blobs with version (>= 5.2.0)'

Hi @Chavan, Shweta ,

Thanks for reaching out to Microsoft Q&A.

WorkerExtensions.csproj : error NU1102: Unable to find package Microsoft.Azure.WebJobs.Extensions.Storage.Blobs with version (>= 5.2.0)

This error is usually not caused by your project file directly.

The Azure Functions Worker SDK generates a temporary WorkerExtensions.csproj during build, and that generated project restores extension packages required by your triggers. For Blob triggers, it may internally reference Microsoft.Azure.WebJobs.Extensions.Storage.Blobs even in isolated worker apps.

A few things stand out in your setup:

1. .NET Framework 4.8 + Isolated Worker is not supported

The isolated worker model supports .NET (Core/5+/6+/8+) runtimes, not .NET Framework 4.8. If you're creating a new isolated function app, use:

<TargetFramework>net8.0</TargetFramework>

or another supported .NET version.

2. Verify NuGet package sources

Microsoft.Azure.WebJobs.Extensions.Storage.Blobs 5.2.0 definitely exists on NuGet.

If the error is NU1102: Unable to find package Microsoft.Azure.WebJobs.Extensions.Storage.Blobs with version (>= 5.2.0), then most commonly:

• nuget.org is disabled
• Package Source Mapping is blocking the package
• corporate/private feeds are being used and nuget.org isn't searched
• proxy/firewall restrictions exist

Check:

dotnet nuget list source

or Visual Studio:

Tools
 -> NuGet Package Manager
 -> Package Sources

Ensure nuget.org is enabled.

3. Check for Package Source Mapping

If your solution has a NuGet.Config, look for <packageSourceMapping>

Most of the times, WorkerExtensions restore fail because the generated project attempts to restore packages that aren't mapped to any source. Similar WorkerExtensions restore failures have been reported when package source restrictions prevent extension packages from being restored.

You could try:

<PackageReference Include="Microsoft.Azure.Functions.Worker.Sdk"
                  Version="2.0.2"
                  OutputItemType="Analyzer" />

as a test.

5. Clean generated WorkerExtensions files

Delete bin/ obj/ ,then run:

dotnet nuget locals all --clear 
dotnet restore

After a failed build, open:

obj\Debug\net8.0\WorkerExtensions\WorkerExtensions.csproj

and inspect which package versions are being generated. That file usually reveals exactly why the SDK is requesting:

Microsoft.Azure.WebJobs.Extensions.Storage.Blobs 5.2.0

even though your project references:

Microsoft.Azure.Functions.Worker.Extensions.Storage.Blobs 6.2.0

Hope this helps!

If the resolution was helpful, kindly take a moment to click on and click on Yes for was this answer helpful. And, if you have any further query do let us know.

Hello Chavan, Shweta,

Welcome to the Microsoft Q&A and thank you for posting your questions here.

I understand that your new Azure function (with .net 8) isolated model (Blob trigger),, azure function v4 is showing error 'WorkerExtensions.csproj : error NU1102: Unable to find package Microsoft.Azure.WebJobs.Extensions.Storage.Blobs with version (>= 5.2.0)'

The project model conversion might give you more issue, and to avoid any misconceptions. The required resolution is NuGet source/source-mapping correction. NuGet error NU1102 means the required package version is not available from the configured feeds, or package source mapping prevents NuGet from using the source where the package exists. - https://learn.microsoft.com/en-us/nuget/reference/errors-and-warnings/nu1102, https://learn.microsoft.com/en-us/nuget/consume-packages/package-restore

The best practice resolution is to:

• Keep the Azure Function as NET 8 isolated model.
• Keep the Blob trigger package as Microsoft.Azure.Functions.Worker.Extensions.Storage.Blobs.
• Do not add Microsoft.Azure.WebJobs.Extensions.Storage.Blobs directly to the isolated app project as the main fix.
• Enable nuget.org, or mirror Microsoft.Azure.WebJobs.Extensions.Storage.Blobs version 5.2.0 or later into the approved internal feed.
• Fix any NuGet package source mapping that excludes Microsoft.Azure.WebJobs.* or Microsoft.Azure.Functions.*.
• Clear NuGet caches, delete generated bin and obj folders, then restore and rebuild.

After the correct NuGet source is available and package source mapping is corrected, the generated WorkerExtensions.csproj restore succeeds and the .NET 8 isolated Blob trigger project builds successfully.

Use the below official resource links for more reading and implementation steps:

• Azure Blob storage bindings for Azure Functions: - https://learn.microsoft.com/en-us/azure/azure-functions/functions-bindings-storage-blob
• Azure Blob storage trigger for Azure Functions: - https://learn.microsoft.com/en-us/azure/azure-functions/functions-bindings-storage-blob-trigger
• .NET isolated worker guide for Azure Functions: - https://learn.microsoft.com/en-us/azure/azure-functions/dotnet-isolated-process-guide
• NuGet error NU1102 official explanation: - https://learn.microsoft.com/en-us/nuget/reference/errors-and-warnings/nu1102
• NuGet package restore behavior: - https://learn.microsoft.com/en-us/nuget/consume-packages/package-restore
• NuGet Package Manager options in Visual Studio: - https://learn.microsoft.com/en-us/nuget/consume-packages/nuget-visual-studio-options

I hope this is helpful! Do not hesitate to let me know if you have any other questions, steps or clarifications.

Please don't forget to close up the thread here by upvoting and accept it as an answer if it is helpful.

This might be caused by the Azure Functions build process, which generates a temporary WorkerExtensions.csproj file and that generated project still references older WebJobs extension packages internally, including Microsoft.Azure.WebJobs.Extensions.Storage.Blobs.

The problem could be attributed to one of the following:

Your NuGet sources cannot resolve the required package version.

A private/company NuGet feed is overriding nuget.org and does not contain the package.

Azure Functions Core Tools or Visual Studio tooling is outdated.

There is a version mismatch between the Azure Functions runtime and the Worker SDK packages.

Btw. .NET Framework 4.8 is not supported with the isolated worker model. Azure Functions isolated worker is intended for .NET 6, .NET 8, and newer. Using .NET Framework 4.8 can cause the tooling to generate incompatible extension references internally.

Your package versions are also likely part of the issue. The 2.0.0 Worker packages are newer and can cause compatibility problems depending on the installed Functions tooling version. The more stable combination for Azure Functions v4 isolated is currently:

Microsoft.Azure.Functions.Worker 1.22.0

Microsoft.Azure.Functions.Worker.Sdk 1.17.2

Microsoft.Azure.Functions.Worker.Extensions.Storage.Blobs 6.2.0

Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore 1.3.1

Start by creating the Function App as

Azure Functions v4

Isolated worker model

.NET 8

Then delete the existing bin and obj folders.

Clear the NuGet cache by running dotnet nuget locals all --clear

Then verify nuget.org is enabled by running dotnet nuget list source

You should see:

https://api.nuget.org/v3/index.json

If your organization uses Azure Artifacts or another private feed, it may be blocking the required Microsoft package versions. In many cases, NU1102 is resolved simply by re-enabling nuget.org or moving it higher in priority.

Finally, run dotnet restore and rebuild the project.

If the above response helps answer your question, remember to "Accept Answer" so that others in the community facing similar issues can easily find the solution. Your contribution is highly appreciated.

hth

Marcin