ASP.NET Core website on Azure fails to start with a 502.5 error after upgrade from .NET Core 1.1.1 to .NET Core 1.1.2

Question

I have a .NET Core web application which I deploy as an Azure Web App.

This has been working perfectly until last night when I applied the Visual Studio 2017 upgrade (v1

Answer 1

We are having the same issue after the Visual Studio 2017 Update.

A workaround is to edit the web.config for your site in Kudu after it has been deployed.

Add --fx-version 1.1.1 at the start of the arguments value for the aspNetCore entry under system.webServer

e.g <aspNetCore processPath="%LAUNCHER_PATH%" arguments="--fx-version 1.1.1 PATH_TO_DLL" stdoutLogEnabled="true" stdoutLogFile=".\logs\stdout" forwardWindowsAuthToken="false"/>

Answer 2

Until they get around to deploying 1.1.2 to the web app images I managed to fix this by forcing the project to reference Microsoft.NETCore.App 1.1.1

Edit the csproj file:

<ItemGroup> <PackageReference Update="Microsoft.NETCore.App" Version="1.1.1" /> <PackageReference Include="Microsoft.ApplicationInsights.AspNetCore" Version="2.0.0" /> <PackageReference Include="Microsoft.AspNetCore" Version="1.1.1" /> ... etc

Answer 3

Update 5/12/2017: we have accelerated the deployment of 1.1.2 and 1.0.5 to App Service and it is now complete. So the workaround below should no longer be needed by anyone.

Original solution

The best workaround is to set this in your .csproj file:

<TargetFramework>netcoreapp1.1.1</TargetFramework>

Instead of it being set to netcoreapp1.1. We will have 1.1.2 deployed to Azure App Service by Tuesday, at which point the workaround won't be necessary.

Note that if if you set it to netcoreapp1.1.1, once 1.1.2 is available it will auto-roll forward to that. So setting it to netcoreapp1.1.1 does not keep you 'stuck' to that version. This is true as long as you use Portable mode (i.e. rely on the framework that's on the OS). If you use standalone and deploy your own framework, then you would be stuck to it (but then you would not have had this issue in the first place and would not have needed to do that!).