X open studio fails to start

I cleared nuget cache. Did x install studio and when I run x run studio,
I see,
Application startup exception: System.NullReferenceException: Object reference not set to an instance of an object.
at ServiceStack.ServiceStackHost.OnStartupException(Exception ex) in C:\Source\Servicestack\src\ServiceStack\ServiceStackHost.cs:line 1040
at ServiceStack.ServiceStackHost.g__RunPreConfigure|40_4(Object instance) in C:\Source\Servicestack\src\ServiceStack\ServiceStackHost.cs:line 272
at System.Collections.Generic.List1.ForEach(Action1 action)
at ServiceStack.ServiceStackHost.Init() in C:\Source\Servicestack\src\ServiceStack\ServiceStackHost.cs:line 278
at ServiceStack.NetCoreAppHostExtensions.UseServiceStack(IApplicationBuilder app, AppHostBase appHost) in C:\Source\Servicestack\src\ServiceStack\AppHostBase.NetCore.cs:line 406
at Web.Startup.Configure(IApplicationBuilder app, IWebHostEnvironment env) in C:\src\dotnet-app\src\Web\Startup.cs:line 3566
— End of stack trace from previous location —
at Microsoft.AspNetCore.Hosting.ConventionBasedStartup.Configure(IApplicationBuilder app)
at Microsoft.AspNetCore.HostFilteringStartupFilter.<>c__DisplayClass0_0.b__0(IApplicationBuilder app)
at Microsoft.AspNetCore.Hosting.WebHost.BuildApplication()
Object reference not set to an instance of an object.
I am working on an Intel Mac, when i use x --version, I get,
Version: 6.0.0 ServiceStack: 5.133 Framework: .NET 6.0.0-rtm.21522.10 OS: Unix 11.6.1
Any clues to fix this issue is appreciated.

It’s because you’ve upgraded x tool to v6 (.NET 6) when Studio is built against .NET 5, you’d need to revert back to the previous v5.x version:

$ dotnet tool uninstall -g x
$ dotnet tool install --global x --version 5.1.33

We’ll look at upgrading to Studio at the start of next year as it will break everyone running it with their existing x or app tools and I expect lots of people will wait after Xmas holidays before installing/upgrading to .NET 6.

Even better, I published the latest version that works with v6 x/app tools to studio6 which you can open with any of:

$ x open studio6
$ app open studio6

Or from browser (Windows)