How to Enable 64-bit version of IIS Express in Visual Studio?

When you launch a web project in Visual Studio, by default is uses the 32-bit version of IIS Express. To change that you can enable the 64-bit version through Options.

Tools -> Options -> search for IIS -> tick Use the 64 bit version of IIS Express for web sites and projects.

Could not load file or assembly or one of its dependencies. Access is denied.

This specific error appears to have several possible causes, such as:

1. Incorrect NTFS permissions on the "temporary asp.net" folder
2. Incorrect NTFS permissions on the website folder (location where the .NET client files are located/downloaded from)
3. Aggressive anti-virus product, on the client PC, affecting the files inside the temporary asp.net folder
4. Windows indexing service adversely affecting the temp asp.net folder
5. Microsoft 'Shadow Copy' service is causing a failure.

To fix the permission issue in scenario 1:

Scenario #1

1. Navigate to folder'C:\WINDOWS\Microsoft.NET\Framework\v4...\Temporary ASP.NET Files' 
2. Delete all the files inside this folder
3. Right-click on folder 'Temporary ASP.NET Files', and choose 'properties'
4. Click 'Security' tab
5. Highlight group 'Users'
6. Tick the box 'Allow' next to the permission type 'Full Control'
7. Click 'Apply' then 'OK'
8. If above permission change doesn't work, then add group "IIS_IUSRS" and give it full control permission.