In order to help you migrate from beta4 to beta5, these are the following steps it took me, based on the research/findings.

Environment

• PowerShell run: $env:DNX_FEED="https://www.nuget.org/api/v2"
• PowerShell run: dnvm install 1.0.0-beta5
• PowerShell run: dnvm use 1.0.0-beta5 -p (not sure if its needed however i had to)

Project

• Open global.json and update sdk to 1.0.0-beta5 should look like this:

  {
      "projects": [ "src", "test" ],
      "sdk": {
          "version": "1.0.0-beta5"
      }
  }
  

• Open project.json:

  • Updated dependencies versions from beta4 to beta5

  • Change Configuration dependency from:

    "Microsoft.Framework.ConfigurationModel.Json": "1.0.0-beta4"
    

    to

    "Microsoft.Framework.Configuration": "1.0.0-beta5",
    "Microsoft.Framework.Configuration.Json": "1.0.0-beta5"
    

  • Remove Microsoft.VisualStudio.Web.BrowserLink.Loader
  • Rename _GlobalImport.cshtml to _ViewImports.cshtml

Startup.cs changes

• Change Configuration breaking changes

  • Change namespace from using Microsoft.Framework.ConfigurationModel; to using Microsoft.Framework.Configuration;

  • Change Configuration.GetSubKey to Configuration.GetConfigurationSection

  • Change CTOR to:

    public Startup(IHostingEnvironment env, IApplicationEnvironment appEnv)
    {           
        // Setup configuration sources.
        var configBuilder = new ConfigurationBuilder(appEnv.ApplicationBasePath)
        .AddJsonFile("config.json")
        .AddEnvironmentVariables();
    
        Configuration = configBuilder.Build();
    }
    

  • Remove app.UseBrowserLink();

Project DNU CMDs

• Open PowerShell within app root
• Run dnu restore
• Run dnu build
• Closing and reopening VS at this point helps sometimes.

Myself found it quite difficult to upgrade an existing project, couldn't find all steps required all together. Hope it helps!

To complete, if you want to update from beta 4 to beta 6, see the Stephen Lautier's answer and to this after :

To update from beta 5 to beta 6 :

I did :

• Open global.json and update sdk to "1.0.0-beta6" and save this file
• Visual Studio 2015 proposes to download beta6, click on Yes

In project.json :

• change dnx451 (or dnx452) to dnx46 (To use Framework 4.6)
• replace all "-beta5" with "-beta6" in this file
• remove Microsoft.Framework.ConfigurationModel.UserSecrets

In Startup.cs, if you use Session :

• replace app.UseInMemorySession(...) with app.UseSession()

• In ConfigureServices, add this :

   services.AddCaching();
   services.AddSession();
   services.ConfigureSession(o => {    o.IdleTimeout = TimeSpan.FromSeconds(10); });
  

• Right click on your Project > Properties > Debug > Add a new Environment Variable :

Name : DNX_IIS_RUNTIME_FRAMEWORK

Value : dnx46

See that for more information : http://jameschambers.com/2015/07/launching-an-asp-net-5-application-from-visual-studio-2015/

• In Package Manager Console, write this "dnu restore" and this "dnu build"
• Restart Visual Studio

My project work in beta6 after that, maybe there are other things to do.

After speaking with @davidfowl from the ASP.NET vNext team, he told me that Browser Link doesn't work in beta5 and should be removed.