Jtdcftul

I had the same problem and seeing the logs in /var/log/syslog I had an error for pulseaudio daemon:

[pulseaudio] module.c: Module "module-switch-on-connect" should be loaded once at most. Refusing to load.

So I opened /etc/pulse/default.pa and edited it using # to disable 3 lines:

#.ifexists module-switch-on-connect.so

#load-module module-switch-on-connect

#.endif

Maybe it'ś not the best solution but it solved my trouble.

I have solved this by reinstalling pulseaudio.

Pay attention: if you have some custom edits inside /etc/pulse, they get lost if executing rm -rf /etc/pulse as shown below! In my case there are only a hand full of files that have been reinstalled.

• apt-get remove --purge pulseaudio


• rm -rf /etc/pulse


• apt-get install pulseaudio


• reboot

This also deinstalled some other packages (like oss*) which have not been reinstalled.

I had the exact same problem (same symptoms) and ended up wasting hours looking for a solution. I solved the issue by editing default.pa to statically load modules and replaced hw:1,0 with hw:0,0

sudo nano /etc/pulse/default.pa

Content to change:

load-module module-alsa-sink device=hw:0,0  

load-module module-alsa-source device=hw:0,0  

load-module module-null-sink  

load-module module-pipe-sink  

Save and exit, then run:

sudo alsa force-reload  

pulseaudio -k  

start-pulseaudio-x11  

Hopefully you have sound at this point.

I managed to get the audio again, but the volume controls does not work any more neither the icon in tray appears.

I reinstalled completely the pulseaudio, and in the same way alsa, as in @ChristophS' answer:

• apt-get remove --purge pulseaudio


• rm -rf /etc/pulse


• apt-get install pulseaudio


• reboot

Also edited the lines as in @Carla sousa's answer:

So I opened /etc/pulse/default.pa and edited it using # to disable
3 lines:

#.ifexists module-switch-on-connect.so

#load-module module-switch-on-connect

#.endif

Then, I went to the system configuration as follows:

After that, to the Hardware > Multimedia section:

And finally, I chose the build in driver:

As i said before, I got the sound again. But I cannot control it. Some idea?

I ran into same problem. After installing pavucontrol I restarted my system and now it's detecting my sound card and headphones.

sudo apt-get install pavucontrol

In case pavucontrol giving errors after installation, restart your system and they will gone.

Hope this helps others too.

try to find in .config/ if there another folder that config the pulse
in my case it was
google-chrome-remote-desktop app, that was create another profile with pulse-audio config that prevent the normal profile to load

I'm having the same problem in Kubuntu 17.10. I cannot say what the cause was, it happened after I plugged in the HDMI cable or after I paired a bluetooth speaker and changed the output audio stream to it.
After some searches I mixed up some solutions. Audio seems to work now but I'm wondering if this is a good or bad solution. What I did was:

• sudo apt-get remove --purge pulseaudio


• sudo rm -rf /etc/pulse


• sudo apt-get install pulseaudio


• sudo reboot

Audio was up but there was no way to control it. Icon in the system tray disappeard. So I did:

• sudo apt-get install plasma-pa


• sudo reboot

At the reboot the icon was in the system tray but audio was mute and not working, exactly like here. So I removed plasma-pa and installed kmix. Doing this, audio is working now.

• sudo apt-get remove plasma-pa


• sudo apt-get install kmix

Is this a good solution? What's the problem with plasma-pa?

Thanks,
Luca

@peterling 's answer worked for me it is the last one on this page: askubuntu.com/questions/70560/why-am-i-getting-this-connection-to-pulseaudio-failed-error

He said I had to enter this in the terminal:

sudo pulseaudio -k

pulseaudio --start

this is what it looked like on the terminal:

lubuntu@lubuntu:~$ sudo pulseaudio -k

E: [pulseaudio] core-util.c: Home directory not accessible: Permission denied

E: [pulseaudio] main.c: Failed to kill daemon: No such file or directory

lubuntu@lubuntu:~$ pulseaudio --start

N: [pulseaudio] main.c: User-configured server at {2d68ac8ceac9497599efde6fcfca4f8c}unix:/run/user/999/pulse/native, which appears to be local. Probing deeper

After this I ran pulseaudio volume control From using the normal shortcut by clicking on it in lUbuntu 16.10
You're using a much newer version of KUbuntu but I think this might work for you because we have this in common:
"

I tried start-pulseaudio-x11. Output:

Connection failure: Connection refused

pa_context_connect() failed: Connection refused

"

Don't have enough rep to comment, but I tried the 3rd solution above by ChristophS. While this looks like a good solution, on Kubuntu 18.10 using purge uninstalled my plasma-desktop and kubuntu-desktop. I had a bunch of unnecessary packages listed from a wine uninstall, I plan to reinstall. Needless to say caused quite the confusion, especially paired with the permission changes which ended up being the cause, which I thought messed with the desktop.

Lesson being: be careful what you purge! I think there should be a comment on the above solution to warn about the current inclusion of desktop with purge pulseaudio.

apt -s remove --purge pulseaudio

Purg kubuntu-desktop [1.379]

Purg plasma-pa [4:5.13.5-0ubuntu2]

Purg plasma-desktop [4:5.13.5-1ubuntu4]

Purg libcanberra-pulse [0.30-6ubuntu1]

Purg pavucontrol-qt [0.4.0-1]

Purg pulseaudio-module-bluetooth [1:12.2-0ubuntu4]

Purg pulseaudio [1:12.2-0ubuntu4]

If hack from the above link works, might be the permissions:
HOME=/tmp/$USER pulseaudio --start