I know that this is an extreme edge case but figured that anyone that's as curious as we are on Blazor and Razor components might run into this issue.

If you happen to build a Block that will end up rendering a Razor component with server interactivity you may end up with the following exception and stacktrace:

System.InvalidOperationException: The current thread is not associated with the Dispatcher. Use InvokeAsync() to switch execution to the Dispatcher when triggering rendering or component state.
         at Microsoft.AspNetCore.Components.Dispatcher.AssertAccess()
         at Microsoft.AspNetCore.Components.HtmlRendering.Infrastructure.StaticHtmlRenderer.WriteComponentHtml(Int32 componentId, TextWriter output)
         at Microsoft.AspNetCore.Components.Endpoints.EndpointHtmlRenderer.WriteComponentHtml(Int32 componentId, TextWriter output, Boolean allowBoundaryMarkers, SequenceAndKey sequenceAndKey)
         at Microsoft.AspNetCore.Components.Endpoints.EndpointHtmlRenderer.WriteComponentHtml(Int32 componentId, TextWriter output)
         at Microsoft.AspNetCore.Components.Endpoints.EndpointHtmlRenderer.PrerenderedComponentHtmlContent.WriteTo(TextWriter writer, HtmlEncoder encoder)
         at Microsoft.AspNetCore.Mvc.ViewFeatures.Buffers.ViewBuffer.WriteTo(TextWriter writer, HtmlEncoder encoder)
         at EPiServer.Web.Mvc.Html.Internal.WrappedHtmlContent.WriteTo(TextWriter writer, HtmlEncoder encoder)
         at Microsoft.AspNetCore.Mvc.ViewFeatures.Buffers.ViewBuffer.WriteToAsync(TextWriter writer, HtmlEncoder encoder)
         at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderLayoutAsync(ViewContext context, ViewBufferTextWriter bodyWriter)
         at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderLayoutAsync(ViewContext context, ViewBufferTextWriter bodyWriter)
         at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderAsync(ViewContext context)
         at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext viewContext, String contentType, Nullable`1 statusCode)
         at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext viewContext, String contentType, Nullable`1 statusCode)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResultFilterAsync>g__Awaited|30_0[TFilter,TFilterAsync](ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResultExecutedContextSealed context)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.ResultNext[TFilter,TFilterAsync](State& next, Scope& scope, Object& state, Boolean& isCompleted)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeResultFilters()
      --- End of stack trace from previous location ---
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|25_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync()
      --- End of stack trace from previous location ---
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
         at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
         at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
         at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)
         at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)
         at EPiServer.Cms.Shell.UI.Internal.RegisterAdminUserMiddleware.InvokeAsync(HttpContext context)
         at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)
         at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)
         at EPiServer.Middleware.InitializeOnFirstRequestMiddleware.InvokeAsync(HttpContext httpContext)
         at EPiServer.Framework.DependencyInjection.Internal.VisitorGroupMiddleware.Invoke(HttpContext httpContext)
         at Microsoft.WebTools.BrowserLink.Net.BrowserLinkMiddleware.InvokeAsync(HttpContext context)
         at Microsoft.AspNetCore.Watch.BrowserRefresh.BrowserRefreshMiddleware.InvokeAsync(HttpContext context)
         at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ProcessRequests[TContext](IHttpApplication`1 application)

This issue seems to occur when you're rendering this block in a contentarea using @Html.PropertyFor(m => m.MyContentArea).
If you change @Html.PropertyFor to @Html.DisplayFor or use the new epi-property-taghelper - this problem does not take place.

Just to clarify, a block vith a view like this:
CounterBlock.cshtml

@model CounterBlock

<h3>Hello Counter Block</h3>
<component type="typeof(Counter)" render-mode="ServerPrerendered" />

cannot be rendered using @Html.PropertyFor.

ArticlePage.cshtml

@* This works *@
<div epi-property="CurrentContent.MainBody" />

@* This works *@
@Html.DisplayFor(x => x.CurrentContent.MainBody)

@* This also works *@
@{ Html.RenderContentArea(Model.CurrentContent.MainBody); }

@* But this does not work *@
@Html.PropertyFor(x => x.CurrentContent.MainBody)

I pushed my examples to a new empty CMS site if anyone wants run this themselves: https://github.com/KevinJCandlert/epi-razor-component-issue/tree/master