Allen - Following your directions, here is what I found:
Wi-Fi tab, preferred Networks -There were no networks shown. It was blank.
Keychain Access - there were no AirPort network passwords, or any other reference to AirPort, under any heading or column. I did find 2 references to a past and current router, I deleted them, then re-booted.
When the system came up, it appeared that the same problem persisted. I went into network/assist me to establish a new connection w/my network. I went thru the routine a few times, and continuously got the same response “the password is incorrect”. I used my desktop to check on the password shown on my router, and I was entering the correct password. I had to do another home task, so just left everything as it was.
About an hour later, I came back to see if I had properly gone over your instructions, and noted the WiFi “fan” in the top of the monitor was black, indicating wi-fi connection. Started Safari. It spun on the home page (yahoo) for awhile, then brought it in! Wanting to make sure this wasn’t a “fluke” I quit Safari, and started Firefox. My Verizon home page came right up.
So Allen, it would seem you have DID IT!! I hope anyone who has said they are experiencing WiFi issues since the recent updates read this and apply your magic solution.
Thank you so much - I was seriously thinking of putting my MBPro up for sale on eBay. Oltekkie