[wix-users] (deprecated) Error loading prerequisite bootstrapper application because managed host could not be loaded

[Brian C C. <ton...@gm...>]

I am getting "Error loading prerequisite bootstrapper application because
managed host could not be loaded" in the logs of my custom bootstrapper.
Originally I was using burn 3.9.2, and receiving error code 0x80004001. On
the advice of this thread (http://tinyurl.com/pt9ym65) I tried upgrading to
3.10.0.1823 but am still receiving the same error, only with a different
error code: 0x80131700.

My bootstrapper is targeting .NET 3.5 and is installing 4.5 as a
prerequisite.  Curiously enough, I am initially able to install .NET 4.5,
and load my custom bootstrapper.  However, if I subsequently uninstall .NET
via ARP, and run my bootstrapper a 2nd time, then I consistently get the
above error.  The test environment is running Windows 7 with .NET 3.5
enabled.  Here is my bootstrappercore.config

<?xml version="1.0" encoding="utf-8" ?>
<configuration>

  <configSections>
    <sectionGroup name="wix.bootstrapper"
type="Microsoft.Tools.WindowsInstallerXml.Bootstrapper.BootstrapperSectionGroup,
BootstrapperCore">
      <section name="host"
type="Microsoft.Tools.WindowsInstallerXml.Bootstrapper.HostSection,
BootstrapperCore" />
    </sectionGroup>
  </configSections>

  <startup useLegacyV2RuntimeActivationPolicy="true">
    <supportedRuntime version="v4.0" />
  </startup>

  <wix.bootstrapper>
    <host assemblyName="MyBootstrapperApplication">
      <supportedFramework version="v3.5" />
    </host>
  </wix.bootstrapper>

</configuration>

Can someone please advise whether this is a WiX bug or I am doing something
wrong?  Thanks in advance.

Brian