Incompatible with DeveloperExceptionPageMiddleware (ASP.NET 5)

[justdmitry]

In my Startup.cs I have Configure method like this:

app.UseIISPlatformHandler();
app.UseStaticFiles();
app.UseDeveloperExceptionPage();
app.UseIdentity()
app.UseRequestLocalization(...);
app.UseWebMarkupMin();
app.UseMvc(...);

I use WebMarkupMin only for MVC content (because all static files are already compressed/minified), but I want to use DeveloperExceptionPageMiddleware (app.UseDeveloperExceptionPage()) earlier in pipeline, because I want it to handle exceptions in identity/auth/... middleware too.

With this config, if any exception occurs (in MVC) - server returns blank page and I see exception in console window from DeveloperExceptionPageMiddleware:

fail: Microsoft.AspNet.Diagnostics.DeveloperExceptionPageMiddleware[0]
An exception was thrown attempting to display the error page.
System.ArgumentException: Stream was not writable.
at System.IO.StreamWriter..ctor(Stream stream, Encoding encoding, Int32 bufferSize, Boolean leaveOpen)
at Microsoft.AspNet.Diagnostics.Views.BaseView.d__28.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.AspNet.Diagnostics.DeveloperExceptionPageMiddleware.d__7.MoveNext()

I guess this happens because WebMarkupMin already wrote compressed content (empty page?) into output response stream, and DeveloperExceptionPageMiddleware can't re-write this stream again.

Exception page shows successfully if I move UseDeveloperExceptionPage() after UseWebMarkupMin(), like this:

app.UseWebMarkupMin();
app.UseDeveloperExceptionPage();
app.UseMvc(...)

But I lose any details about exceptions in non-MVC middleware.

[justdmitry]

I tried to place UseDeveloperExceptionPage() immediately before UseWebMarkupMin() - problem still here, DeveloperExceptionPageMiddleware fails and error page not rendered.

This means that other middleware (UseIdentity, UseRequestLocalization) are not "guilty".

[Taritsyn]

Hello, Dmitry!

In WebMarkupMin 2.0.0 RC 5 fixed this error.

Thanks for information!