Unable to load the metadata for assembly ''. This assembly may have been downloaded from the web. See http://go.microsoft.com/fwlink/?LinkId=179545. The following error was encountered during load: Could not load file or assembly '' or one of its dependencies. Operation is not supported. (Exception from HRESULT: 0x80131515)

Solution: 

Unable to load the metadata for assembly ''. This assembly may have been downloaded from the web. See http://go.microsoft.com/fwlink/?LinkId=179545.  The following error was encountered during load: Could not load file or assembly '' or one of its dependencies. Operation is not supported. (Exception from HRESULT: 0x80131515)

In WPF project to allow the project to load from remote source we have to enable it in the configuration file devenv.exe.config.

Step 1: Search the configuration file devenv.exe.config in your system. Usually it is located at

C:\Program Files\Microsoft Visual Studio 10.0\Common7\IDE\devenv.exe.config

Step 2: Edit the configuration file. Add following line in the <runtime> tag

<loadFromRemoteSources enabled="true" />

Step3: Restart your visual studio.