我使用bitbucket将我的功能应用程序部署到azure：当我在bitbucket中签入master时，我的代码将部署到azure。
这很好，但现在我升级了我的功能应用程序从.net核心2.2到3.1和。。。
现在我有个例外：

Command: "D:\home\site\deployments\tools\deploy.cmd"
Handling function App deployment with dotnet.exe.
D:\Program Files (x86)\dotnet\sdk\2.2.109\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.TargetFrameworkInference.targets(137,5): error NETSDK1045: The current .NET SDK does not support targeting .NET Core 3.1.  Either target .NET Core 2.2 or lower, or use a version of the .NET SDK that supports .NET Core 3.1. [D:\home\site\repository\xxxxxx\xxxxxx\xxxxxx.csproj]
D:\Program Files (x86)\dotnet\sdk\2.2.109\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.TargetFrameworkInference.targets(137,5): error NETSDK1045: The current .NET SDK does not support targeting .NET Core 3.1.  Either target .NET Core 2.2 or lower, or use a version of the .NET SDK that supports .NET Core 3.1. [D:\home\site\repository\xxxxxx\UnitTest\UnitTest.csproj]
Failed exitCode=1, command=dotnet restore "D:\home\site\repository\xxxxxx\xxxxxx.sln"
An error has occurred during web site deployment.
\r\nD:\Program Files (x86)\SiteExtensions\Kudu\85.11226.4297\bin\Scripts\starter.cmd "D:\home\site\deployments\tools\deploy.cmd"

所以它说它不支持.NETCore3.1
这是一个明显的错误，因为我刚刚更新了它。
但我不知道是什么给了我这个错误。我无法想象这是azure的抱怨，因为他们确实支持.NETCore3.1(https://docs.microsoft.com/en-us/azure/azure-functions/functions-versions). 我也无法想象源代码是内置的bitbucket（是吗？），bitbucket不支持.NETCore3.1？
我找到了一些关于“kudu”这个词的信息。似乎它在azure上，负责从git到azure的部署。所以现在我想知道为什么kudu不支持.netcore3.1
编辑2：我列出的框架：

D:\home>dotnet --list-runtimes
Microsoft.AspNetCore.All 2.1.14 [D:\Program Files (x86)\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.15 [D:\Program Files (x86)\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.2.8 [D:\Program Files (x86)\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.1.14 [D:\Program Files (x86)\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.15 [D:\Program Files (x86)\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.2.8 [D:\Program Files (x86)\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.0.1 [D:\Program Files (x86)\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.0.2 [D:\Program Files (x86)\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.1.0 [D:\Program Files (x86)\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.1.1 [D:\Program Files (x86)\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 1.0.16 [D:\Program Files (x86)\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 1.1.13 [D:\Program Files (x86)\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.0.9 [D:\Program Files (x86)\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.14 [D:\Program Files (x86)\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.2.8 [D:\Program Files (x86)\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 3.0.2 [D:\Program Files (x86)\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 3.1.1 [D:\Program Files (x86)\dotnet\shared\Microsoft.NETCore.App]

编辑3：
会不会是这个host.json错了？

{
    "version": "2.0"
}

没有读到它必须改变，但也许？