WiFi password can be entered but won't connect with no error message

I was having similar problems. I was able to resolve it by going to the edit connection page for the connection in question and entering both the password and security type (WPA in my case) in the Wi-Fi Security tab.

You can access the edit connection page through the drop down on the Wi-Fi icon at the top of the desktop (after already having attempted to connect); or by clicking the orange arrow on the far right of that connection under the listing of wireless connections within the network manager.

TL:DR

Can see routers SSID, But computer asks for a password again and again.

Computer has (b)/(g) wifi

Router has (n) Wifi

Router settings may be in Greenfield Mode.

Greenfield Mode BAD!

If you are having a problem connecting to your router, especially on an old computer that runs on (b) or (g) wifi, check to see if your routers radio settings are set to greenfield Mode. This mode will ignore all (b) and (g) wifi as noise and only work with (n) capable devices. It also is quite destructive, as it can "Shout over" (b) and (g) wifi signals, so enabling it is a bit of a bad neighbour move, even if all your devices support (n) wifi only.

The symptoms are similar to what is described by others on this topic, that being that you can see the SSID of your network, but it will just ask for a password again and again without an error.

I experienced the same issue in Ubuntu 16.04 and Linux Mint 18.

What I suggest to you is to follow these steps:

• go to Network Settings
• choose the network you are trying to connect to
• under the security tab, enter the wifi password manually
• save it

You are not the only one impacted. I wrote about it here and you can see that multiple have been affected by it, even the Arch Linux users.

Eventually I changed the authentication to PEAP (from TTLS - tunelled TLS) which worked.