Ensure that your web.config matches the one in the release package https://bugnet.codeplex.com/SourceControl/latest#src/BugNET_WAP/Web.config, especially the binding redirects section:
<dependentAssembly>
<assemblyIdentity name="DotNetOpenAuth.Core" publicKeyToken="2780ccd10d57b246" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-4.3.0.0" newVersion="4.3.0.0" />
</dependentAssembly>