Service Won't Start

How to diagnose and fix a Linux service that won't start or crashes continuously

Check service status

systemctl status service-name

The output shows if the service is active (running), failed, or inactive.

Read the service logs

# Last 50 logs
journalctl -u service-name -n 50

# Real-time logs (useful to see what happens on restart)
journalctl -u service-name -f

# Logs from last system boot
journalctl -u service-name -b

Basic systemd commands

# Start
systemctl start service-name

# Stop
systemctl stop service-name

# Restart
systemctl restart service-name

# Reload configuration without downtime
systemctl reload service-name

# Enable on automatic startup
systemctl enable service-name

# Disable automatic startup
systemctl disable service-name

Diagnosis for specific service

Nginx won't start

# Test configuration
nginx -t

# See the specific error
journalctl -u nginx -n 20

Common causes:

Syntax error in configuration file
Port 80 or 443 already used by another process
SSL certificate file missing or expired

Apache won't start

apache2ctl configtest
journalctl -u apache2 -n 20

MySQL / MariaDB won't start

journalctl -u mariadb -n 30
# or
cat /var/log/mysql/error.log | tail -30

Common causes:

Disk full (MySQL can't write)
Database corruption (after a crash)
Wrong configuration in /etc/mysql/

To repair corrupted tables:

mysqlcheck --all-databases --auto-repair -u root -p

PHP-FPM won't start

journalctl -u php8.2-fpm -n 20
php-fpm8.2 --test

Port already in use

Often a service won't start because its port is already in use:

# Who uses port 80?
ss -tlnp | grep :80

# or
lsof -i :80

# Kill the process using the port
kill -9 PID

Service crashes in loop

If a service keeps crashing, systemd puts it in "failed" state after a while:

# Reset failure counter
systemctl reset-failed service-name

# Then restart
systemctl start service-name

Services in failed state

# List all services in error
systemctl --failed

Permission problem

Sometimes a service won't start because it doesn't have permissions on its files:

# Check file owner (example for nginx)
ls -la /var/www/example.com/
ls -la /etc/nginx/

# Fix permissions
chown -R www-data:www-data /var/www/example.com/
chmod -R 755 /var/www/example.com/

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