Winforms Designer not working after upgrading from .NET Framework to .NET 8 with the migration assistant

Question

I've upgraded a Winforms application from .NET Framework to .NET 8 using the migration assistant. The program runs fine in debug mode, with the forms working.

The problem is that when I go to the designer for the forms, it isn't working. I have the same error message for every form and, in fact, I've tried adding a new, blank form and still get the same error.

Error:

The type name:" properties" on the property:"Name" of type:"System.CodeDom.CodeNamespace" is not a valid language-independent type name. (Parameter 'e')

Call stack:

at StreamJsonRpc.JsonRpc.d__154`1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.DotNet.DesignTools.Client.Host.ServerHost.d__16.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.DotNet.DesignTools.Client.DesignToolsClientLoader.d__29.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.DotNet.DesignTools.Client.DesignToolsClientLoader.<>c__DisplayClass25_1.<<-ctor>b__1>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.DotNet.DesignTools.Client.DesignToolsClientLoader.d__27.MoveNext()

I've read other posts where people are having migration issues related to the Winforms designer, but none seem to solve my issue. Any help is appreciated.

Visual Studio WinForm Designer not working after .Net Framework migration to .Net Core

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