Website Troubleshooting – Deep Dive Across Servers, Frameworks & Stacks

Website failures are rarely caused by a single issue. Most production outages happen due to multiple small misconfigurations across layers. This guide helps you systematically isolate, diagnose, and fix issues across infrastructure, web servers, runtimes, frameworks, and databases.

Golden Rule of Troubleshooting

Never guess. Always validate layer by layer.

The fastest fixes come from knowing where to look first.

Layer 1: DNS & Network-Level Troubleshooting

Typical Symptoms

• Website loads for some users but not others

• Domain works with IP but not with name

• SSL fails intermittently

Deep Checks

dig example.com +short
dig example.com NS
dig example.com MX

Check propagation:

dig @8.8.8.8 example.com
dig @1.1.1.1 example.com

Real-World Causes

• Wrong A/AAAA records after migration

• Old IP cached at ISP level

• Cloudflare proxy misconfiguration

• Domain expired or nameservers incorrect

Layer 2: Server Availability & Resource Exhaustion

Before touching Apache, PHP, or code — check the server itself.

Core System Checks

top
htop
df -h
free -m

What to Look For

• CPU constantly > 90% → runaway process

• Memory almost full → PHP-FPM / Node crash

• Disk 100% full → logs, backups, or emails

• Swap heavily used → memory pressure

Real-World Scenarios

• Cron jobs consuming CPU

• Backup scripts filling disk

• Email queues exhausting storage

• Log rotation misconfigured

Layer 3: Web Server Troubleshooting (Apache / Nginx)

Common Error Codes & Meaning

Log-First Approach

# Apache
tail -f /var/log/apache2/error.log
tail -f /var/log/httpd/error_log

# Nginx
tail -f /var/log/nginx/error.log

Typical Root Causes

• Wrong root or DocumentRoot

• PHP-FPM socket mismatch

• SELinux blocking access

• Incorrect .htaccess rules

Layer 4: PHP Runtime & PHP-FPM Issues

Symptoms

• White page

• 500 error

• Random crashes under load

Validate PHP Environment

php -v
php -m
php --ini

Check PHP-FPM:

systemctl status php-fpm
journalctl -u php-fpm

Common Production Failures

• PHP version upgraded but extensions missing

• Memory limit exceeded

• OPcache misconfiguration

• Wrong PHP-FPM user/group

Layer 5: WordPress-Specific Troubleshooting

Most Common Issues

• White Screen of Death (WSOD)

• Plugin conflicts after updates

• Database connection errors

Immediate Recovery Steps

1. Disable plugins:

mv wp-content/plugins wp-content/plugins.disabled

2. Enable debug logging:

define('WP_DEBUG', true);
define('WP_DEBUG_LOG', true);
define('WP_DEBUG_DISPLAY', false);

3. Check logs:

wp-content/debug.log

Real-World Failures

• PHP version incompatible with old plugins

• Theme using deprecated functions

• Corrupted wp_options table

Layer 6: Laravel Troubleshooting (Production Focus)

High-Frequency Errors

• 500 Internal Server Error

• Storage permission denied

• Cache/config mismatch

Mandatory Checks

php artisan key:generate
php artisan config:clear
php artisan cache:clear
php artisan route:clear

Permissions:

chown -R www-data:www-data storage bootstrap/cache
chmod -R 775 storage bootstrap/cache

Production Reality

• .env missing or incorrect

• Cached config after environment change

• Queue workers not running

Layer 7: Node.js / React / Next.js Troubleshooting

Symptoms

• App runs locally but not on server

• PM2 app keeps restarting

• Build fails on production

Core Diagnostics

node -v
npm -v
pm2 status
pm2 logs

Common Causes

• Node version mismatch

• Missing environment variables

• Memory limit exceeded

• Incorrect build output path

Layer 8: Database Troubleshooting (MySQL / MariaDB / PostgreSQL)

Typical Errors

• Connection refused

• Too many connections

• Slow queries

Quick Checks

systemctl status mysql
mysql -u user -p
SHOW PROCESSLIST;

Disk I/O:

iostat

Real-World Problems

• Database running out of disk space

• Large tables without indexes

• Corrupted tables after crash

• Wrong bind-address

Layer 9: SSL / HTTPS Issues

Symptoms

• HTTPS warning

• Redirect loop

• Mixed content errors

Verification

openssl s_client -connect example.com:443

Check certificate:

certbot certificates

Common Mistakes

• SSL installed but site URLs still HTTP

• Double redirects (Apache + app)

• Expired certificate after migration

Layer 10: Performance & Slow Website Troubleshooting

Key Metrics

• CPU load

• Memory usage

• Disk I/O

• PHP-FPM workers

• Database query time

Live Monitoring

top
htop
df -h
free -m

Optimization Areas

• Enable OPcache

• Use Redis/Memcached

• Add CDN

• Optimize images

• Database indexing

Structured Troubleshooting Workflow

1. Check DNS & network

2. Verify server health

3. Inspect web server logs

4. Validate runtime (PHP/Node)

5. Debug framework/CMS

6. Confirm database health

7. Fix SSL & security

8. Optimize performance

Conclusion

Effective website troubleshooting is about methodology, not luck. By isolating issues layer by layer and using logs as the primary source of truth, administrators can resolve outages faster and prevent repeat incidents.