Step 1: Connect to the server<\/h3>\n
Log in to your virtual machine over SSH first.<\/p>\n
ssh root@<your-server-ip><\/p>\n
Once you are connected, you can start checking the services and logs.<\/p>\n
Step 2: Check the web server<\/h3>\n
Start by confirming that the web server is running.<\/p>\n
For Nginx:<\/p>\n
sudo systemctl status nginx<\/p>\n
sudo systemctl start nginx<\/p>\n
For Apache on Ubuntu or Debian:<\/p>\n sudo systemctl status apache2<\/p>\n For Apache on AlmaLinux or CentOS:<\/p>\n sudo systemctl status https<\/p>\n If Apache is stopped, start the service and verify whether the website becomes accessible again.<\/p>\n Even if Nginx or Apache is running, the site will still fail if the backend app is down.<\/p>\n If the app is managed by PM2:<\/p>\n pm2 status<\/p>\n If it runs as a system service:<\/p>\n systemctl status your-service<\/p>\n For PHP apps, check PHP-FPM too, for example:<\/p>\n sudo systemctl status php8.1-fpm<\/p>\n sudo systemctl restart php8.1-fpm<\/p>\n A stopped PHP-FPM service is one of the most common reasons for 502 errors on PHP-based sites.<\/p>\n Logs usually tell you what is actually wrong.<\/p>\n For Nginx:<\/p>\n sudo tail -f \/var\/log\/nginx\/error.log<\/p>\n Common messages include:<\/p>\n For Apache, check the relevant error log:<\/p>\n Ubuntu or Debian:<\/p>\n sudo tail -f \/var\/log\/apache2\/error.log<\/p>\n AlmaLinux or CentOS:<\/p>\n sudo tail -f \/var\/log\/httpd\/error_log<\/p>\n You should also check application logs:<\/p>\n pm2 logs<\/p>\n journalctl -u your-service<\/p>\n These logs often show whether the app failed to start, crashed, or simply took too long to respond.<\/p>\n If the server is under heavy load, the backend may respond too slowly and trigger a gateway error.<\/p>\n Check CPU usage:<\/p>\n top<\/p>\n Check memory:<\/p>\n free -h<\/p>\n Check disk space:<\/p>\n df -h<\/p>\n If CPU, RAM, or disk space is consistently high, stop unnecessary services or upgrade the VM if needed.<\/p>\n Instead of testing through the browser, hit the backend from the server itself.<\/p>\n curl http:\/\/127.0.0.1:3000<\/a><\/p>\n If you get a response, the backend is reachable. If the command fails or hangs, the app may be down or listening on a different port.<\/p>\n If the web server and backend are both running, make sure traffic between them is not being blocked.<\/p>\n You can also verify the firewall rules from the Network<\/b> section of your VM in AccuWeb.Cloud portal. You can follow the firewall guide here: Configure firewall rules for a virtual machine<\/a>.<\/p>\n![\"\"](\"https:\/\/accuweb.cloud\/resource\/wp-content\/uploads\/2026\/07\/Step-2-Check-the-web-server.png\")
<\/a><\/p>\n<\/a><\/p>\nStep 3: Check the backend application<\/h3>\n
<\/a><\/p>\n<\/a><\/p>\nStep 4: Review the logs<\/h3>\n
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<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\nStep 5: Check server resources<\/h3>\n
<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\nStep 6: Test the backend directly<\/h3>\n
<\/a><\/p>\nStep 7: Check firewall settings<\/h3>\n