A very long time ago, I had FoxitReader.
If I try to open a PDF from Firefox, then E throws up a window about not being able to open FoxitReader.
Note, Firefox is set to use evince as the default application.
I tracked down the FoxitReader.desktop file in .local/share/applications/FoxitReader.desktop and deleted it.
Now, E tries to open PDFs with ephoto, which was installed to /usr/local/bin/ephoto. I wasn't using it, so I deleted that, too.
But E still tries to open ephoto anyway. I've checked Default Applications.
application/pdf is set to Document Viewer (which should be evince).
Name : enlightenment-git
Version : 0.23.0.23606.ged924301b-1
Build Date : Fri 19 Jul 2019 11:03:04 PM EDT
Install Date : Fri 19 Jul 2019 11:35:01 PM EDT
Name : efl-git
Version : 18.104.22.168697.gbf01c2382a-1
Build Date : Fri 19 Jul 2019 10:56:53 PM EDT
Install Date : Fri 19 Jul 2019 11:03:02 PM EDT