# Step 1 — Check Nginx Status

First, see the current status:

sudo systemctl status nginx

Look for:

• Active: inactive (dead)

• Failed to start messages

• Errors at the bottom

Example output:

● nginx.service - A high performance web server
   Loaded: loaded (/lib/systemd/system/nginx.service; disabled)
   Active: failed (Result: exit-code)

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## Step 2 — Test Nginx Configuration

A common reason Nginx won’t start is a syntax error in the configuration.

Run:

sudo nginx -t

You might see:

nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
nginx: configuration file /etc/nginx/nginx.conf test failed

Fix any errors reported here before proceeding.

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## Step 3 — Check for Port Conflicts

Nginx usually uses ports 80 (HTTP) and 443 (HTTPS). If another process is using the port, Nginx won’t start.

Check which process uses port 80:

sudo lsof -i :80

Or:

sudo netstat -tulpn | grep :80

If you see Apache, another Nginx instance, or any process using the port:

• Stop the conflicting service:

sudo systemctl stop apache2
sudo systemctl stop nginx   # stop old instance if needed

• Or change Nginx port in /etc/nginx/sites-available/default

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## Step 4 — Check Logs for Errors

Nginx logs are in /var/log/nginx/.

Check error log:

sudo tail -n 50 /var/log/nginx/error.log

Look for:

• Missing files (e.g., certificate, HTML)

• Syntax errors in virtual host configs

• Permission issues

• 
  

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## Step 5 — Fix Permission Issues

Nginx may fail to start if it cannot read files.

Check ownership and permissions:

sudo chown -R www-data:www-data /var/www/html
sudo chmod -R 755 /var/www/html

For SSL certificates:

sudo chmod 600 /etc/ssl/private/*.key
sudo chmod 644 /etc/ssl/certs/*.crt

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## Step 6 — Restart Nginx Safely

After fixing configuration and permissions:

sudo systemctl restart nginx

Check status:

sudo systemctl status nginx

It should show:

Active: active (running)

Test by opening your website in a browser or:

curl http://localhost

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## Step 7 — Check SELinux or Firewall (if applicable)

Sometimes Nginx cannot bind to ports due to security restrictions.

Check firewall

sudo ufw status

Allow HTTP/HTTPS:

sudo ufw allow 80/tcp
sudo ufw allow 443/tcp

Check SELinux (CentOS/RHEL)

sestatus

If enabled, allow Nginx to bind ports:

sudo setsebool -P httpd_can_network_connect 1

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## Step 8 — Remove Old PID Files

If Nginx was killed improperly, old PID file may block startup:

sudo rm /var/run/nginx.pid
sudo systemctl start nginx

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## Step 9 — Test Configuration After Every Change

Always test config before restarting:

sudo nginx -t

If “syntax is ok” → restart Nginx safely.

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## Step 10 — Beginner-Friendly Checklist

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## Conclusion

Nginx not starting is a common problem but almost always fixable with careful troubleshooting. By following these beginner-friendly steps, you can:

• Identify configuration errors

• Resolve port conflicts

• Fix file permission issues

• Check firewall and SELinux restrictions

• Restart Nginx safely

With these steps, your websites should be running again in no time.