I have 3 API projects repo'd in devops and hosted on windows 2016 servers (App Services) that were using the app service continuous deployment sync functionality. So far, everyday i have deployed small code changes to all three environments. One by one each of these projects has failed to deploy via this method. I upgraded these projects a few months ago to .NET8, and made the coorelating changes to the service to support that with no issue. The Error I am getting is below. C:\Program Files (x86)\MSBuild-16.4\MSBuild\Current\Bin\Microsoft.Common.CurrentVersion.targets(1175,5): error MSB3644: The reference assemblies for .NETFramework,Version=v8.0 were not found. To resolve this, install the Developer Pack (SDK/Targeting Pack) for this framework version or retarget your application. You can download .NET Framework Developer Packs at https://aka.ms/msbuild/developerpacks I am not sure how to interact with the msbuild in this manor, nor do I fully understand what the issue is all of a sudden. In the meantime I've been utilizing pubx profiles.

The error indicates a build error, not a deployment one. Can you confirm that the build is failing and not the deployment? The error looks like to me a mismatch of frameworks. Did you happen to upgrade this project from NET Framework 4.x to NET 8? There is no NET Framework 8 which is what the error seems to be indicating to me. Migrating from NF 4.x to NET 8 is not a simple change in the target version. For example the project property identifying the framework changes from TargetFrameworkVersion to TargetFramework . Of course all this should be caught during the build.

MSBuild 16.4 MSB3644 Error .NET 8 Deployment Center Sync

Accepted answer

Michael Taylor 48,311 Reputation points

2024-04-11T14:20:53.84+00:00

The error indicates a build error, not a deployment one. Can you confirm that the build is failing and not the deployment?

The error looks like to me a mismatch of frameworks. Did you happen to upgrade this project from NET Framework 4.x to NET 8? There is no NET Framework 8 which is what the error seems to be indicating to me. Migrating from NF 4.x to NET 8 is not a simple change in the target version. For example the project property identifying the framework changes from TargetFrameworkVersion to TargetFramework. Of course all this should be caught during the build.
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Ables, Bradley 35 Reputation points

2024-04-11T16:41:23.16+00:00

Thanks for reaching out Michael. This project was on .NET7 maybe 4 months ago, but has been on .net8 for a bit now. This project builds fine locally, pubx deploys fine as well. so i guess my misunderstanding is why when sync is this an issue?

Michael Taylor 48,311 Reputation points

2024-04-11T16:53:14.3033333+00:00

When exactly do these errors occur? Is it in the middle of publishing the app to your servers? If so can you share with us the process and tools you're using to publish.

If it happens after the app is deployed while you're trying to load it in the browser then I'd lean toward an IIS issue. In that case please clarify what type of app you are dealing with (MVC, ASPNET Web API, ASPNET Core MVC, etc.)

Ables, Bradley 35 Reputation points

2024-04-11T19:41:41.77+00:00

I'm using the deployment center sync option within the app service itself. Which I am seeing is somewhat of a Blackbox event.

This is an ASP.NET API hosted on a webapp service.

In the deployment center of the app I have linked continuous deployment to my azure devops repo and branch.

This process typically has build and deployed the code updates. Logs were visible via the deployment center logs screen.

Michael Taylor 48,311 Reputation points

2024-04-11T20:18:59.6933333+00:00

I cannot answer to issues with the deployment center stuff. We don't use that feature. I would suggest you take a look at your settings to see if it is not properly configured to build the NET 8 project. But perhaps somebody else can guide you on getting deployment center working.

Ables, Bradley 35 Reputation points

2024-04-12T12:15:53.2266667+00:00

Thank you for trying!

ANKIT THAKUR 10 Reputation points

2024-04-12T14:20:54.79+00:00

Is this a recent issue ? I've been getting the same issue ever since a create a new app service for a lower environment and used the existing to create a build using azure deployment center. the source of the code is my azure repository. The same code is working on a different environment but if I branch it use is on a new app service I am unable to build my code. I have not upgraded my project, it was always on .NET8.0 to begin with, but I am facing this issue today. I have did something exactly the same 15 days ago and had no issues. So why is Azure Deployment Center not able to figure out reference libraries now ?

Ables, Bradley 35 Reputation points

2024-04-12T14:25:57.7866667+00:00

This just started last friday for me. and slowly this week each of my envs have begun to fail. I am not aware of any changes to this process on their side. Not sure what the issue is here.

ANKIT THAKUR 10 Reputation points

2024-04-12T15:18:14.6266667+00:00

not sure if this helps, but I was able to select the version of sdk to use by creating global.json file at the root of the project .

https://learn.microsoft.com/en-us/dotnet/core/tools/global-json

James Barton 6 Reputation points

2024-04-14T00:27:52.8966667+00:00

Super weird, same exact thing just started happening for me at the exact same time! No update to .net version or anything as I've been on .net 8 for months too. Microsoft, one of your web servers has had the .net 8 libraries removed loool!?

James Barton 6 Reputation points

2024-04-14T00:44:41.66+00:00

Adding global.json didn't work for me either, details here: https://stackoverflow.com/questions/78322382/new-error-on-azure-deployment-error-msb3644-the-reference-assemblies-for-netf

ANKIT THAKUR 10 Reputation points

2024-04-15T05:34:52.6766667+00:00

I got it working by updating the Msbuild path is deploy to cmd.

MSBUILD_1670_DIR was available which is MS build v 17.8.6

just update this line is deply.cmd and you should be good.

call :ExecuteCmd "C:\Program Files (x86)\MSBuilds\17.8.6\MSBuild\Current\Bin\MSBuild.exe" /restore "%DEPLOYMENT_SOURCE%\SmartAssets.Server\SmartAssets.Server.csproj" /p:DeployOnBuild=true /p:configuration=Release /p:publishurl="%DEPLOYMENT_TEMP%" %SCM_BUILD_ARGS%

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ANKIT THAKUR 10 Reputation points

2024-04-15T06:15:14.7133333+00:00

to add a custom deployment script . you can check this reference.

https://stackoverflow.com/questions/59275634/set-msbuild-to-version-15-in-azure-app-service

James Barton 6 Reputation points

2024-04-16T23:03:16.2166667+00:00

That worked, thanks Ankit
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MSBuild 16.4 MSB3644 Error .NET 8 Deployment Center Sync

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