Sorry to hear that. It is very strange, because in the past there was a bug, which didn’t allow to use GroupDocs.Comparison in IIS under the virtual directory, but it was fixed a long time ago. I double checked it today, with the WebForms project, hosted under IIS 7.5, as the Virtual Application, which, in turn, is located inside the Virtual Directory; all is working fine without modifying paths in the HTTP-handler descriptor in the web.config or additional configuring. So your error is really strange.
Can you please check the following things:
1. What exact version of the GroupDocs.Comparison you are using? I mean assembly version, which can be found in the reference properties in the MS Visual Studio.
2. Which project from the “Comparison Samples” package you are using? You’ve deployed it to the IIS “as is”, or this project contains some modifications? If yes, can you send us that project?
Thanks and waiting for your response.
I think that the fact that you’re using an old version 188.8.131.52 is the reason. We physically cannot provide support for old and obsolete versions. Can you please try to use the latest version 184.108.40.206 and try to reproduce this issue with it? If this problem still will be present, we will review your project and will be working on it.