How To Fix “Jack Server is not running or cannot be started” Error in Ubuntu

In this article, we will be addressing a common error experienced by Ubuntu users: “Jack Server is not running or cannot be started”. This error is often encountered when trying to use audio applications that rely on the JACK Audio Connection Kit. We will provide several potential solutions, each with step-by-step instructions.

Understanding the Error

Before we dive into the solutions, it’s important to understand what the error message means. The JACK Audio Connection Kit, or JACK, is a sound server daemon that provides real-time, low-latency connections for both audio and MIDI data between applications. If you’re seeing this error, it means that the JACK server is either not currently running, or it’s encountering issues when trying to start.

Solution 1: Restart PulseAudio and JACK

The first solution we’ll explore involves restarting both PulseAudio and JACK. PulseAudio is a sound server for POSIX and Win32 systems, and it can sometimes interfere with JACK.

Open your terminal and run the following commands:

pulseaudio --kill
jack_control start
jack_control exit
pulseaudio --start

Here’s what each command does:

• pulseaudio --kill: This command stops the PulseAudio process.
• jack_control start: This command starts the JACK Control process.
• jack_control exit: This command stops the JACK Control process.
• pulseaudio --start: This command restarts the PulseAudio process.

Solution 2: Use pasuspender with qjackctl

Another solution is to use the pasuspender command with qjackctl. This command temporarily suspends PulseAudio, allowing qjackctl to run without interference.

In your terminal, run the following command:

pasuspender qjackctl

Once you’re done with qjackctl, PulseAudio will automatically restart.

Solution 3: Disable Real-Time Priorities for JACK

If the above solutions don’t work, you can try disabling real-time priorities for JACK. Real-time priorities can sometimes cause issues with JACK if they’re not properly configured.

To start JACK without real-time priorities, run the following command in your terminal:

jackd -r &

If you have qjackctl installed, you can also disable real-time priorities through the GUI. Simply uncheck the “Realtime” option in the “Setup” section.

Solution 4: Configure Real-Time Priorities for JACK

If disabling real-time priorities doesn’t solve the issue, you might need to configure them instead. This involves editing a configuration file and adding yourself to a new user group.

First, open the configuration file by running the following command in your terminal:

sudo nano /etc/security/limits.d/99-realtime.conf

Then, add the following lines to the file:

@realtime - rtprio 99
@realtime - memlock unlimited

Press Ctrl+o to save the file and Ctrl+x to exit.

Next, create a new user group called ‘realtime’ and add yourself to it:

sudo groupadd realtime
sudo usermod -a -G realtime yourUserID

Remember to replace ‘yourUserID’ with your actual user ID. You’ll need to log out and log back in for the changes to take effect.

Solution 5: Set the Interface in the JACK Control GUI

Finally, you can try setting the interface in the JACK Control GUI. This involves specifying the hardware interface that JACK should use.

To do this, open the JACK Control GUI and go to the “Setup” section. Set the “Interface” to hw:PCH (or the appropriate interface for your system).

Conclusion

We hope this guide has helped you resolve the “Jack Server is not running or cannot be started” error in Ubuntu. If you’re still experiencing issues, consider reaching out to the Ubuntu community for further assistance. Remember, troubleshooting is a process of elimination, so don’t get discouraged if the first solution doesn’t work. Keep trying until you find the one that does.

pulseaudio --kill
jack_control start
jack_control exit
pulseaudio --start

pasuspender qjackctl

jackd -r &

@realtime - rtprio 99
@realtime - memlock unlimited

sudo groupadd realtime
sudo usermod -a -G realtime yourUserID