# .NET Core 3.0 Preview Known Issues

This document lists known issues for **.NET Core 3.0 Preview releases** which may be encountered during usage.


## ASP.NET Core

### Preview 3
- **The Windows Hosting bundle doesn't exist for Preview3**: The Windows Hosting bundle contained an issue which copied the 32 bit dlls into 64 bit locations. To work aroud this issue, please install the 3.0 Preview 2 [Hosting Bundle](https://github.com/dotnet/core/blob/master/release-notes/3.0/preview/3.0.0-preview2-download.md) and run the executable on a command line with the paramaters `OPT_NO_SHAREDFX=1 OPT_NO_RUNTIME=1`. Then install the appropriate .NET and ASP.NET runtimes for preview3.

- **Updates to .razor files fail to show up in subsequent builds**: Updates to Razor Component (.razor) in Visual Studio may fail to show up in subsequent builds. To work around this issue add the following item group to the project file:

    ```xml
    <ItemGroup>
        <UpToDateCheckInput Include="@(Content->WithMetadataValue('Extension', '.razor'))" />
    </ItemGroup>
    ```

- **Updates to Razor Components in .razor files fail to show up in IntelliSense**: Updates to Razor Components defined in .razor files may fail to show up in IntelliSense in Visual Studio. To workaround this issue rebuild the project.

- **Single Page Applications with authentication enabled throws method not found exception when visiting the register or login pages**: The exception message is the one below.
`Method not found: 'Microsoft.EntityFrameworkCore.Metadata.Builders.IndexBuilder Microsoft.EntityFrameworkCore.Metadata.Builders.EntityTypeBuilder``1.HasIndex(System.Linq.Expressions.Expression``1<System.Func``2<!0,System.Object>>)'.` To workaround this issue follow these steps:
  * Replace the following package references with the ones below in your csproj folder:
    ```xml
    <PackageReference Include="Microsoft.AspNetCore.Identity.EntityFrameworkCore" Version="3.0.0-preview3-19153-02" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="3.0.0-preview3.19153.1" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="3.0.0-preview3.19153.1" />
    ```

    ```xml
    <PackageReference Include="Microsoft.AspNetCore.Identity.EntityFrameworkCore" Version="3.0.0-preview-18579-0056" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="3.0.0-preview.19080.1" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="3.0.0-preview.19080.1" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Relational" Version="3.0.0-preview.19080.1" />
    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="3.0.0-preview.19080.1" />
    ```

  * Add the following snippet to your csproj file:
    ```xml
    <PropertyGroup>
      <NoWarn>$(NoWarn);NU1605</NoWarn>
    </PropertyGroup>
    ```
    
- **Referencing 3.0.0 MVC libraries don't work as intended**: There are several issues with referencing a 3.0.0 MVC library.

    * Razor pages will 404, 
    * ApplicationParts and factories will not be discoverable
    * Controllers will not be discoverable

    To workaround this issue do the following:

    * Add the helper method:
    ```C#
    private void Add30AssemblyWorkaround(Assembly referencedAssembly, ApplicationPartManager applicationPartManager)
    {
        var partFactory = ApplicationPartFactory.GetApplicationPartFactory(referencedAssembly);

        foreach (var part in partFactory.GetApplicationParts(referencedAssembly))
        {
            applicationPartManager.ApplicationParts.Add(part);
        }

        var relatedAssemblies = RelatedAssemblyAttribute.GetRelatedAssemblies(referencedAssembly, throwOnError: true);
        foreach (var assembly in relatedAssemblies)
        {
            partFactory = ApplicationPartFactory.GetApplicationPartFactory(assembly);
            foreach (var part in partFactory.GetApplicationParts(assembly))
            {
                applicationPartManager.ApplicationParts.Add(part);
            }
        }
    }
    ```

    * Modify your `services.AddMvc()` call in `Startup.cs`:
    ```C#
    services.AddMvc()
        .ConfigureApplicationPartManager(manager =>
        {
            var referencedAssembly = Assembly.Load("RCL");
            Add30AssemblyWorkaround(referencedAssembly, manager);
        })
        ...
    ```

- **React template with authentication has a syntax error on build** in file /ClientApp/src/components/api-authorization/ApiAuthorizationConstants.js
When building or running the react template with authentication, after opening the browser, the app won't work and the following error message will be displayed.
  ```console
  ×
  Error: Module build failed: SyntaxError: ClientApp/src/components/  api-authorization/ApiAuthorizationConstants.js: Unexpected token (27:25)
  
    25 |   DefaultLoginRedirectPath: '/',
    26 |   ApiAuthorizationClientConfigurationUrl: `/_configuration/$ {ApplicationName}`,
  > 27 |   ApiAuthorizationPrefix = prefix,
       |                          ^
    28 |   Login: `${prefix}/${LoginActions.Login}`,
    29 |   LoginFailed: `${prefix}/${LoginActions.LoginFailed}`,
    30 |   LoginCallback: `${prefix}/${LoginActions.LoginCallback}`,
  ```
  * Workaround:
  Replace `ApiAuthorizationPrefix = prefix,` with `ApiAuthorizationPrefix: prefix,`

- **Import error "Cannot find module "./components/api-authorization/Login"**: When building or running the react template with authentication, after opening the browser, the app won't work and the following error message will be displayed.
  ```console
  ×
  Error: Cannot find module "./components/api-authorization/Login"
  ▼ 13 stack frames were expanded.
  ./src/components/api-authorization/ApiAuthorizationRoutes.js
  https://localhost:44315/static/js/bundle.js:53166:7
  __webpack_require__
  ClientApp/webpack/bootstrap 43633f0e2b726d97cc14:678
  fn
  ClientApp/webpack/bootstrap 43633f0e2b726d97cc14:88
  ./src/App.js
  https://localhost:44315/static/js/bundle.js:51925:111
  __webpack_require__
  ClientApp/webpack/bootstrap 43633f0e2b726d97cc14:678
  fn
  ClientApp/webpack/bootstrap 43633f0e2b726d97cc14:88
  ./src/index.js
  https://localhost:44315/static/js/bundle.js:54708:63
  __webpack_require__
  ClientApp/webpack/bootstrap 43633f0e2b726d97cc14:678
  fn
  ClientApp/webpack/bootstrap 43633f0e2b726d97cc14:88
  0
  https://localhost:44315/static/js/bundle.js:54860:18
  __webpack_require__
  ClientApp/webpack/bootstrap 43633f0e2b726d97cc14:678
  (anonymous function)
  ClientApp/webpack/bootstrap 43633f0e2b726d97cc14:724
  (anonymous function)
  https://localhost:44315/static/js/bundle.js:728:10
  ```

  * Workaround:
    * Remove the file /ClientApp/src/components/api-authorizationApi/AuthorizationRoutes.js
    * Replace the contents of App.js with these
      ```javascript
      import React, { Component } from 'react';
      import { Route } from 'react-router';
      import { Layout } from './components/Layout';
      import { Home } from './components/Home';
      import { FetchData } from './components/FetchData';
      import { Counter } from './components/Counter';
      import { Login } from './components/api-authorization/Login'
      import { Logout } from './components/api-authorization/Logout'
      import AuthorizeRoute from './components/api-authorization/AuthorizeRoute';
      import { ApplicationPaths, LoginActions, LogoutActions } from './components/api-authorization/ApiAuthorizationConstants';

      export default class App extends Component {
        static displayName = App.name;

        render () {
          return (
            <Layout>
              <Route exact path='/' component={Home} />
              <Route path='/counter' component={Counter} />
              <AuthorizeRoute path='/fetch-data' component={FetchData} />
              <Route path={ApplicationPaths.Login} render={() => loginAction(LoginActions.Login)} />
              <Route path={ApplicationPaths.LoginFailed} render={() => loginAction(LoginActions.LoginFailed)} />
              <Route path={ApplicationPaths.LoginCallback} render={() => loginAction(LoginActions.LoginCallback)} />
              <Route path={ApplicationPaths.Profile} render={() => loginAction(LoginActions.Profile)} />
              <Route path={ApplicationPaths.Register} render={() => loginAction(LoginActions.Register)} />
              <Route path={ApplicationPaths.LogOut} render={() => logoutAction(LogoutActions.Logout)} />
              <Route path={ApplicationPaths.LogOutCallback} render={() => logoutAction(LogoutActions.LogoutCallback)} />
              <Route path={ApplicationPaths.LoggedOut} render={() => logoutAction(LogoutActions.LoggedOut)} />
            </Layout>
          );
        }
      }

      function loginAction(name){
          return (<Login action={name}></Login>);
      }

      function logoutAction(name) {
          return (<Logout action={name}></Logout>);
      }
      ```

- **Runtime compilation using Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation throws an error stating "Cannot find reference assembly"**: When performing runtime Razor compilation, the application throws an error stating reference assemblies cannot be found. To workaround this, edit the project file and add this following property:
  ```xml
  <PropertyGroup>
    <PreserveCompilationReferences>true</PreserveCompilationReferences>
  </PropertyGroup>
   ```