The error indicates that phpMyAdmin is encountering problems during session initialization. Specifically, it’s failing to write session data due to a lack of available space on the device where the session files are stored.

Possible Causes

Disk Space Exhaustion: The most common cause is that the disk where your session data is stored has run out of space.

Incorrect session.save_path: The session.save_path configuration in your PHP settings might be incorrect.

Check Disk Space

First and foremost, check the available disk space on the device where your session files are stored. You can use the df command to view disk space information:

df -h

If the disk is full or nearly full, you’ll need to free up some space by removing unnecessary files or expanding the storage capacity.

Verify session.save_path

Verify that the session.save_path in your PHP configuration is correctly set. Open your php.ini file and ensure that the session.save_path points to a directory with sufficient space. In your case, it’s set to /opt/lampp/temp/.

session.save_path = "/opt/lampp/temp/"

Clear Session Files

If your disk space is limited, you may have accumulated a large number of session files. Clearing old session files can help free up space. Run the following command to delete old session files:

sudo find /opt/lampp/temp/ -type f -name 'sess_*' -delete

Adjust PHP Session Configuration

Consider adjusting other PHP session-related configurations to optimize session management. This might include tweaking the session timeout settings and garbage collection.

Restart Services

After making changes, restart your web server (e.g., Apache) and PHP to apply the modifications:

sudo service apache2 restart
sudo service php7.4-fpm restart   # Replace with your PHP version