I fixed the problem adding this binding redirect to my .config file:
<runtime>
. . .
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<dependentAssembly>
<assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed"
culture="neutral" />
<bindingRedirect oldVersion="4.5.0.0" newVersion="6.0.0.0" />
</dependentAssembly>
</assemblyBinding>
</runtime>
The error message complains about not finding version 4.5.0.0, the current version of Newtonsoft.Json is 6.0.0.0 so the redirect should go from 4.5 to 6.0, not viceversa