Fix "Failed to Start Service" (General Guide)

Step-by-Step Diagnostic Process

Step 1: Get Detailed Error

sudo systemctl status servicename
sudo journalctl -u servicename -e --no-pager
sudo journalctl -u servicename --since "1 hour ago"

Step 2: Check Common Issues

Based on error messages:

# Permission issues
sudo chmod +x /path/to/executable
sudo chown -R serviceuser:serviceuser /var/lib/servicename

# Config syntax errors
servicename -t  # For services with config test
nginx -t
apache2ctl configtest

# Port conflicts
sudo netstat -tlnp | grep LISTEN

# Missing directories
sudo mkdir -p /var/run/servicename
sudo mkdir -p /var/log/servicename

Step 3: Start with Debugging Flags

# Temporarily run service manually
sudo -u serviceuser /usr/sbin/servicename --debug

Step 4: Check Dependencies

# Services that need network, database, etc.
systemctl list-dependencies servicename

# Start required services first
sudo systemctl start mysql
sudo systemctl start servicename

Step 5: Increase Timeout for Slow Services

sudo systemctl edit servicename

[Service]
TimeoutStartSec=300
Restart=on-failure
RestartSec=30

Step 6: Complete Service Reset

sudo systemctl stop servicename
sudo systemctl disable servicename
sudo apt install --reinstall servicename -y
sudo rm -rf /var/lib/servicename  # WARNING: removes data!
sudo systemctl enable servicename --now

Step 7: Check System Resources

df -h
free -h
ulimit -n  # File descriptor limit