An error on upgrading Master Data Services (MDM) from 2017 to 2019 on the website

If you have used Master Data Services (MDM) version 2017

and you upgraded it to version 2019 by doing an in-place upgrade

or by using the same MDM website URL for the new version as for old version,

you might get the error below when you click on "Explorer" on the website.

Oops! Something went wrong.

The view 'Index' or its master was not found or no view engine supports the searched locations. The following locations were searched:
~/Views/Explore/Index.aspx
~/Views/Explore/Index.ascx
~/Views/Shared/Index.aspx
~/Views/Shared/Index.ascx
~/Views/Explore/Index.cshtml
~/Views/Explore/Index.vbhtml
~/Views/Shared/Index.cshtml
~/Views/Shared/Index.vbhtml

Click Email Microsoft, to report this issue to Microsoft Master Data Service team. 

In my case, what helped is cleaning the local browser cache (IE or Chrome)
by clicking Ctrl+Shift+Del once the browser is opened.

Good Luck