Edit & Continue doesn't work
<p>I'm trying to get managed Edit &amp; Continue working (in Visual Studio 2015 v14.0.25425.01 update 3) and it's giving me the dreaded dialog, "<strong>Changes are not allowed in the following cases:</strong>"</p>

<ul>
<li><p>Attached to a process that does not support Edit and Continue on attach.</p>

<ol>
<li>I'm using IISExpress v10.0.14358.1000, on Windows 10.0.10586, x64.</li>
<li>I have 'Use the 64 bit version of IIS express for web sites and project' checked in Tools->Options. (although, i also get the same error with 32-bit iisexpress)</li>
<li>all my code is compiled 'Any CPU'</li>
</ol></li>
<li><p>The code being debugged was optimized</p>

<ol>
<li>Nope, the all the code is built with the DEBUG constant set, and no optimizations.</li>
</ol></li>
<li><p>The assembly being debugged is loaded as domain-neutral</p>

<ol>
<li>Nope, i checked with Process Explorer, the assembly  isn't loaded DomainNeutral.</li>
</ol></li>
<li><p>The assembly being debugged was loaded through reflection.</p>

<ol>
<li>Not sure about this, but it's a regular ASP.NET MVC 5 app.</li>
</ol></li>
<li><p>Intellitrace events and call information is enabled.</p>

<ol>
<li>Nope, intellitrace is disabled in Tools->Options->Intellitrace.</li>
</ol></li>
<li><p>The .NET Runtime this program is running on does not support edit and continue.</p>

<ol>
<li>Not sure. It's built against ".NET Framework 4.6.1", and the first symbol load is "'iisexpress.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\WINDOWS\Microsoft.Net\assembly\GAC_64\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll'"</li>
</ol></li>
</ul>

<p>some other things:</p>

<ul>
<li>in the 'Web' project settings, both the 'ASP.NET' and 'Enable Edit &amp; Continue' checkboxes are set (and none of the others).</li>
<li>i have 'Edit and Continue' enabled in the Debugger settings.</li>
<li>i have compatibility modes disabled in the Debugger settings.</li>
<li>i have tried deleting my .suo files and the .vs directory, cleaning out my temporary directories, doing a full rebuild</li>
</ul>

<p>what else can i try?</p>

<p>PS. if anyone on the VS debugger team is reading this, can i ask a favor? please <strong>kill</strong> this dialog and replace it with something that indicates the <em>actual</em> cause of the problem. You have the debuggee right there, and the solution, you can determine which of these is causing the problem and you can have a button which fixes the problem with a single click.</p>