Apple - Get rid of "The Wi-Fi network ... could not be joined." message
- Go to Spotlight (magnifying glass in top corner) / Finder > Activity Monitor
- Search for SystemUIServer in CPU tab using the search bar located at top right corner
- Force quit it
try connecting after removing any USB device connected. It worked for me.
I followed many tips provided thru various Apple / Mac blogs. I did all of the obvious and logical tips, router, turn-off, turn-on WiFi and my MacBook Air wouldn't connect to my wireless network, or via a Bluetooth hotspot from my phone. It would connect on Bluetooth, even sending a pairing request only to disconnect. I could not load my Network name when choosing a network
So, I connected my iPhone (Did have an active connection to my wireless network) via USB as an option in my Network on the Mac. Then went to: System Preferences > Network. Under location, I went to Edit Location, created a location named "Untitled". Instead of Automatic, I chose "Untitled." I instantly received a password request for my network. I'm now connected and Location has defaulted to Automatic.Removed the iPhone connection and I'm up and running. It wasn't pretty, but it worked.