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在 Xamarin 表单上，我使用的是 Prism MVVM。在对这两个包Microsoft.AspNetCore.SignalR.Client 1.1.0->3.0.0 和 Microsoft.Extensions.Caching.Memory 2.2.0->3.0.0进行一些更新后，我的应用程序只显示白屏。

看不到登录页面。

我只更新这两个包。删除了 bin 和 obj 文件夹，但没有帮助

其他包版本：

Prism.Forms-> 7.2.0.1367

Xamarin.Forms -> 4.2.0.815419

任何想法 ？

编辑： 我正在使用的所有包：

<ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.SignalR.Client">
      <Version>1.1.0</Version>
    </PackageReference>
    <PackageReference Include="Microsoft.Extensions.Caching.Memory">
      <Version>3.0.0</Version>
    </PackageReference>
    <PackageReference Include="NdefLibrary">
      <Version>4.1.0</Version>
    </PackageReference>
    <PackageReference Include="Prism.Core">
      <Version>7.2.0.1367</Version>
    </PackageReference>
    <PackageReference Include="Prism.Forms">
      <Version>7.2.0.1367</Version>
    </PackageReference>
    <PackageReference Include="Prism.Plugin.Popups">
      <Version>7.2.0.573</Version>
    </PackageReference>
    <PackageReference Include="Prism.Unity.Forms">
      <Version>7.2.0.1367</Version>
    </PackageReference>
    <PackageReference Include="Rg.Plugins.Popup">
      <Version>1.1.5.188</Version>
    </PackageReference>
    <PackageReference Include="System.Buffers">
      <Version>4.5.0</Version>
    </PackageReference>
    <PackageReference Include="System.Memory">
      <Version>4.5.3</Version>
    </PackageReference>
    <PackageReference Include="Xam.Plugins.Notifier">
      <Version>3.0.1</Version>
    </PackageReference>
    <PackageReference Include="Xamarin.Android.Support.Design" Version="28.0.0.3" />
    <PackageReference Include="Xamarin.Android.Support.v7.AppCompat" Version="28.0.0.3" />
    <PackageReference Include="Xamarin.Android.Support.v4" Version="28.0.0.3" />
    <PackageReference Include="Xamarin.Android.Support.v7.CardView" Version="28.0.0.3" />
    <PackageReference Include="Xamarin.Android.Support.v7.MediaRouter" Version="28.0.0.3" />
    <PackageReference Include="Xamarin.Essentials">
      <Version>1.3.1</Version>
    </PackageReference>
    <PackageReference Include="Xamarin.Forms" Version="4.2.0.815419" />
    <PackageReference Include="Xamarin.Forms.Visual.Material">
      <Version>4.2.0.815419</Version>
    </PackageReference>
    <PackageReference Include="Xamarin.HotReload">
      <Version>1.4.19</Version>
    </PackageReference>
    <PackageReference Include="ZXing.Net.Mobile">
      <Version>2.4.1</Version>
    </PackageReference>
    <PackageReference Include="ZXing.Net.Mobile.Forms">
      <Version>2.4.1</Version>
    </PackageReference>
  </ItemGroup>

编辑：发现新错误

现在我收到这些错误。我得到这个错误首先删除了signalR并读取它并检查了所有“公共语言运行时异常”

System.TypeLoadException: 'Could not load type of field 
'Microsoft.AspNetCore.Http.Features.Authentication.HttpAuthenticationFeature:<Handler>k__BackingField' (1) 
due to: Could not resolve type with token 01000080 from typeref (
expected class 'Microsoft.AspNetCore.Http.Features.Authentication.IAuthenticationHandler' in assembly 
'Microsoft.AspNetCore.Http.Features, Version=2.2.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60') 
assembly:Microsoft.AspNetCore.Http.Features, Version=2.2.0.0, Culture=neutral, 
PublicKeyToken=adb9793829ddae60 type:Microsoft.AspNetCore.Http.Features.Authentication.IAuthenticationHandler 
member:(null)'

在调试窗口中

**System.TypeLoadException:** 'Could not load type of field 'Microsoft.AspNetCore.Http.Features.Authentication.HttpAuthenticationFeature:<Handler>k__BackingField' (1) due to: Could not resolve type with token 01000080 from typeref (expected class 'Microsoft.AspNetCore.Http.Features.Authentication.IAuthenticationHandler' in assembly 'Microsoft.AspNetCore.Http.Features, Version=2.2.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60') assembly:Microsoft.AspNetCore.Http.Features, Version=2.2.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60 type:Microsoft.AspNetCore.Http.Features.Authentication.IAuthenticationHandler member:(null)'

**System.Reflection.TargetInvocationException:** 'Exception has been thrown by the target of an invocation.'

**Unity.ResolutionFailedException:** 'For more information add Diagnostic extension: Container.AddExtension(new Diagnostic())'

**Prism.Navigation.NavigationException:** 'An error occurred while resolving the page. This is most likely the result of invalid XAML or other type initialization exception'

**Prism.Navigation.NavigationException:** 'An error occurred while resolving the page. This is most likely the result of invalid XAML or other type initialization exception'
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1 回答 1

1

在后面的页面代码中，将 initialiseComponent() 包装在 try catch 中，并查看断点的错误。白屏通常意味着 Xaml 问题

于 2020-03-17T12:18:48.980 回答