Thanks for the detailed info.
1. You’ve said that you are using the “GroupDocs.Viewer_2.4.0_Samples.msi” demo package. This package contains the GroupDocs.Viewer for .NET ver 2.4.0, which is obsolete. The last version of the GroupDocs.Viewer is 2.5.0. Maybe the issue you have is already fixed in the new version, so it would be very useful to download the newest version. You can download it while downloading the new version of the “GroupDocs.Viewer C# Demos”. Alternatively, you can download the pure library and update the reference in your project.
2. You’ve installed the package with the sample project to the “C:\Program Files (x86)</em>…” folder. This is a system folder, and it requires additional permissions from the web-server. GroupDocs.Viewer requires full control over the root storage folder, so this may be a reason of the issue too. Please move the “GroupDocsViewerWebformsDemo” folder, which contains a project with the same name, to the some another location. Then open the project with MS Visual Studio 2013, which was launched with administrator rights, and try out to debug the project one more time.
If these suggestions will not help, please come back to us, and we will continue to find a solution.
Thanks and sorry for the inconvenience.
Thanks for the information. Using the latest dll 2.5.0 fixed the problem.