Why is “Edit in SharePoint Designer” opening in Notepad

Question

I'm following this example - link here

I've gone to Master pages and layouts (_catalogs/masterpage/Forms/AllItems.aspx)

I've created a new page layout, when I hover over to click "Edit in Microsoft SharePoint Designer" the page opens in notepad

I've clicked on a few other aspx pages in this library and they open in Notepad.

But the master pages I clicked on do open in SP Designer.

Update with my answer
I did a Repair on SharePoint Designer and rebooted. Its working now.

Answer 1

I did a Repair on SharePoint Designer and rebooted. Its working now.

Answer 2

In IE go to Tools > Internet Options > Programs and see if "Microsoft SharePoint Designer" is selected as the "HTML Editor".

Also try going through Windows Explorer to Tools > Folder Options > File Types; select ASPX and set the "Opens With" to SharePoint Designer.

Answer 3

Clear your SharePoint Designer cache.

http://www.c-sharpcorner.com/UploadFile/sagarp/how-to-clear-your-sharepoint-designer-20102013-cache/

Then, the Custom workflow will open normally in SharePoint Designer instead of the browser or Notepad.