How to Stop the Ubuntu ‘Wpa_Supplicant’ (Wi-Fi Manager) from Writing Massive Log Files

Why is Wpa_Supplicant Using So Much Disk Space?

In Ubuntu, wpa_supplicant is the background service responsible for managing your Wi-Fi connections, negotiating security keys, and keeping you connected to your router.

Under normal circumstances, it runs quietly in the background. However, if your router has a weak signal, or if there is a subtle incompatibility between your Wi-Fi card driver and the access point, wpa_supplicant can enter a panic loop. It will continuously attempt to reconnect, failing hundreds of times per second, and writing every single failure to the system log (/var/log/syslog). Over a few days, this can generate massive log files (sometimes gigabytes in size), completely filling up your hard drive and crashing the system.

How to Stop Wpa_Supplicant from Flooding the Logs

You can stop this behavior by reducing the verbosity (logging level) of the wpa_supplicant daemon.

1. Open your Ubuntu Terminal (shortcut: Ctrl + Alt + T).
2. You need to edit the service file. Type the following command and press Enter:

sudo nano /lib/systemd/system/wpa_supplicant.service

3. Look for the line that starts with ExecStart=. It usually looks like this:

ExecStart=/sbin/wpa_supplicant -u -s -O /run/wpa_supplicant

4. You need to add the -q (quiet) flag, or multiple -q flags to suppress all non-critical errors. Modify the line to look like this:

ExecStart=/sbin/wpa_supplicant -u -s -qq -O /run/wpa_supplicant

5. Save the file in Nano by pressing Ctrl + O, then Enter, then exit with Ctrl + X.
6. Reload the systemd daemon so it recognises the change:

sudo systemctl daemon-reload

7. Restart the Wi-Fi service:

sudo systemctl restart wpa_supplicant

The -qq flag forces the service to only log absolute critical fatal errors, preventing the endless spam of minor connection warnings from eating your disk space.