I\'m using Visual Studio 2019 version 16.0.4, and I tried to create a view or a partial one on asp.net core 2.1 (in views folder) but I get an error
I was mistaken (24th Update), see comments on this post, it's apparently still broken, either way, the original answer below still works, in both cases.
The answer below still stands if your using an older release of Visual Studio 2019, however please be aware this has now been fixed in the more up-to date releases:
https://developercommunity.visualstudio.com/content/problem/562039/there-are-no-scaffolders-supported-for-this-item-1.html
Original Answer
There's currently a known bug in Visual Studio 2019 for this scenario.
There is some semi official advice on the GitHub issue tracker, but it doesn't always work.
MS Will fix it eventually, there appears to currently be no timescale.
For now however, if you right click and use add new item:
Then pick the item type you want (In my case it's a razor page)
Then you'll find everything still works as expected. The bug only seems to affect the shortcut menus.