asp.net mvc runtime / 500 error outputs encoded garbage to razor page

Question

I'm having issues debugging an mvc5.2.3 project. If there is an error anywhere the page doesn't error out with a nice easy to read error about what just happened. It outputs this character encoded garbage:

��}kw�8��9g�'=�mObI��N��I:y7��R"d�C�j��z��Y�E�,zv�vl �B�� x��O?�뇗ƢZ�O��'Ϳ~�,P7�ӿ��J��|�JҨJ��xYy�d\�9��,Z��W �^�E��Y��uW��]%3tD�x`��eu�+Ϙ��u�8�G�$�9~��(�<��(�\T�Y^,��N��б1��,O��x�F�Ϗo P�j�Ba!˨�L��*_G��-�U��i��%�6��o��@��

my web.config has:

<?xml version="1.0" encoding="utf-8"?>    
<compilation debug="true" targetFramework="4.5" />
<customErrors mode="Off" />

have also tried adding to web.config:

<globalization fileEncoding="utf-8" requestEncoding="utf-8" responseEncoding="utf-8" />

I've also tried updating all packages to their latest versions by running

Update-Package

in the Package Manager Console. Quite a few versions on things were wrong, so I thought this might fix it but no dice...

I know when it outputs like this that I have an error in my code somewhere. I've been ignoring it but as my code gets more complex it's getting more difficult to figure out where any issues are.

Help!

Do you have a global error handler registered that might be mucking with the output before it gets sent out the response stream? — Craig W., Apr 23 '15 at 14:18
just seeing the RegisterGlobalFilters() `public static void RegisterGlobalFilters(GlobalFilterCollection filters) { filters.Add(new HandleErrorAttribute()); }` — Ryan Vettese, Apr 23 '15 at 14:21
Is that the default `HandleErrorAttribute` or have you written your own? — Craig W., Apr 23 '15 at 14:23
it's the default one. taking it out of the Application_Start() doesn't change anything. — Ryan Vettese, Apr 23 '15 at 14:24
not sure how this got fixed but this is not happening any more. weird. — Ryan Vettese, May 28 '15 at 19:11
this is actually still happening on one project of mine. Even in latest Visual Studio. — Ryan Vettese, Apr 26 '16 at 13:48
yes, after nearly 5 years i have finally answered my own question lol. — Ryan Vettese, Dec 02 '19 at 20:49

Ryan Vettese · Accepted Answer · 2019-12-02T20:48:24.307

0

So this can be fixed by disabling gzip compression in IIS. With gzip off and errors on you will see error messages coming through properly.

There are a few good methods mentioned here to disable gzip:

Can gzip compression be selectively disabled in ASP.NET/IIS 7?

My favourite:

<system.webServer>
    ...
    <urlCompression doStaticCompression="true" doDynamicCompression="false" />
</system.webServer>

edited Dec 02 '19 at 20:48

answered Dec 02 '19 at 20:42

Ryan Vettese

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asp.net mvc runtime / 500 error outputs encoded garbage to razor page

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