Can't connect to WiFi with "Connection activation failed" error after upgrade from 14.04 -> 15.04

Question

I recently upgraded from 14.04 to 14.10 to 15.04 in succession. I lost internet capabilities each time, thanks to my having to use a Realtek WiFi dongle.

I was able to resolve those issues both times, but I now have this whenever I try to connect to a network by clicking on the option under the Network Manager applet:

I can connect when manually adding the network, but clicking on an option in the applet gives me the above error message.

I've tried reinstalling network-manager, network-manager-gnome, and wpasupplicant, but that didn't help.

EDIT: Something of note, I get a popup whenever I get to the login screen after rebooting asking me to put in the network password.

This makes me think there's something messed up in something that's creating the configuration files for the network, since it isn't saving the password.

However, I don't know what that would be.

EDIT 2: Another thing of note, if I try to connect to a network I've never connected to before, it just closes the menu and nothing happens the first time. However, if I click after that, it brings up the error.

Answer 1

This worked for me:

sudo apt-get install -d --reinstall network-manager network-manager-gnome wpasupplicant

Then

sudo apt-get purge network-manager network-manager-gnome wpasupplicant

However, this last step removed from my system several packages related to graphic interface and my display manager. It effectively removed cinammon from my system.

Then I did:

sudo apt-get install --fix-missing network-manager network-manager-gnome wpasupplicant

And finally:

sudo apt-get upgrade

After rebooting my computer, I was able to connect to the WiFi network.

In the Edit Connections menu of the taskbar, I clicked on the network I wanted to connect to and I activated both IPv4 (DHCP) and IPv6 (DHCP only). Then I changed , under the General tab:

Connection priority for auto-activation

From 0 to 7.

Then I was able to login to this open network through the browser.

However, after this process, I ended up with Xfce, instead of the cinnamon desktop I had before. I don't like Xcfe at all, but the important thing is to be able to connect now.

This is my hardware and operating system:

scasas@dappcw148:~$ sudo lshw -C network
   *-network                 
   description: Wireless interface
   product: Wireless 8265 / 8275
   vendor: Intel Corporation
   physical id: 0
   bus info: pci@0000:02:00.0
   logical name: wlp2s0
   version: 78
   serial: 74:70:fd:32:e4:a2
   width: 64 bits
   clock: 33MHz
   capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
   configuration: broadcast=yes driver=iwlwifi driverversion=4.15.0-39-generic firmware=34.0.1 ip=172.20.2.2 latency=0 link=yes multicast=yes wireless=IEEE 802.11
   resources: irq:129 memory:ef000000-ef001fff
 *-network
   description: Ethernet interface
   product: Ethernet Connection (4) I219-LM
   vendor: Intel Corporation
   physical id: 1f.6
   bus info: pci@0000:00:1f.6
   logical name: enp0s31f6
   version: 21
   serial: 10:65:30:6a:51:3b
   capacity: 1Gbit/s
   width: 32 bits
   clock: 33MHz
   capabilities: pm msi bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
   configuration: autonegotiation=on broadcast=yes driver=e1000e driverversion=3.2.6-k firmware=0.1-4 latency=0 link=no multicast=yes port=twisted pair
   resources: irq:131 memory:ef200000-ef21ffff


scasas@dappcw148:~$ uname -a
Linux dappcw148 4.15.0-39-generic #42-Ubuntu SMP Tue Oct 23 15:48:01 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

Answer 2

Simply try again to install/reinstall network-manager with all dependeces.

sudo apt-get reinstall network-manager
sudo apt-get build-dep network-manager

ł.o.

Answer 3

Had the exact same problem on Ubuntu 16.04 LTS.

Solved by this answer in a post regarding Ubuntu 14.04.

Problem seems to be in the password prompt/popup. Setting the password in the connection details skipped the password prompt and the connection just worked.