title: Android emulator error: "Device error: System.ComponentModel.Win32Exception (0x80004005): The specified executable is not a valid..."
body: <p>Android emulators worked fine for a long time till today.  I suddenly started getting the following error:</p>
  
  <pre><code>Device error: System.ComponentModel.Win32Exception (0x80004005): The specified executable is not a valid application for this OS platform.
     at System.Diagnostics.Process.StartWithCreateProcess(ProcessStartInfo startInfo)
     at Xamarin.DeviceManager.Common.EmulatorManager.&lt;&gt;c__DisplayClass61_0.&lt;StartProcess&gt;b__0()
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/Hxnl9.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Hxnl9.png" alt="enter image description here"></a></p>
  
  <p>I checked <a href="https://stackoverflow.com/questions/47064105/xamarin-android-error-the-specified-executable-is-not-a-valid-application-for">a similar post</a> and tried its solution.  aapt.exe in directory "C:\Program Files (x86)\Android\android-sdk\build-tools\28.0.3" is fine. 
  I have rebooted Visual Studio and restarted my PC to no avail.
  I am wondering if anyone could offer a tip on how to remedy this.</p>