Verify that the Static Content MIME type .qvpp is added in Microsoft IIS. (See Figure 1)
Open the Internet Information Service (IIS) Manager
Navigate to the QlikView site
Locate MIME Types
Add .qvpp as text/html
Note: The release of QlikView April 2020 SR4 (12.50.20400) now adds the .qvpp MIME type to IIS automatically during installation or upgrade. The previous versions of QlikView April 2020 require the manual addition of the .qvpp MIME type to IIS as described above.
Note: If using IIS, other settings may block the use of the .qvpp file. These settings can be identified using Google Chrome and a HAR trace. Look for 404 errors in the console. Solution provided by @mralbert.
The file C:\Windows\System32\inetsrv\config\applicationHost.config may need to have the .qvpp extension added.