twilfo

I am not 100% sure what fixed the problem, but here is the steps I took:

1. Delete .htaccess file.
2. Cleared the caches of all browsers.

• Firefox – First, I cleared the caches. And then, I opened the Help Menu (click question mark icon), click Firefox Help, and click Refresh Firefox.
• Safari – Cleared the caches.
• Chrome – Cleared the caches.

I restarted all browsers, and I was able to log back in and activate the plugin. The “404: File Not Found” error disappeared.
3. Refreshed the permalinks. This recreated the .htaccess file.

I will mark this topic as resolved.