Upgrading project from 2018.3.7 to 2019.2.13 - Fatal Error! Failed to load Editor resource file.

Hi all. I'm trying to upgrade a project from Unity version 2018.3.7f1 to 2019.2.13f1.

I'm getting an error while trying to load the project. The project begins to load, then I get a popup that says "Fatal Error! Failed to load Editor resource file." (See attached photo)

Things I've tried.

1) Made sure my Unity>Editor>Data>Resources>unity editor resources file is not read-only.

2) I deleted the Library folder, and let Unity generate a new one. This let me open the project once, but when I quit and try to open the project again, it gives me the same error.

What steps should I take to further troubleshoot this issue?