Troubleshooting Common Issues in ISPConfig

? Troubleshooting Guide

Website Issues

500 Internal Server Error

Causes and Solutions:

• .htaccess errors: Check syntax, comment out rules to test
• PHP errors: Enable error display, check PHP error log
• Permission issues: Ensure correct ownership (web1:client1)
• Memory limit: Increase PHP memory_limit
• ModSecurity: Check if WAF is blocking request

# Check error log
tail -f /var/www/clients/client1/web1/log/error.log

# Test .htaccess
mv .htaccess .htaccess.backup

# Fix permissions
chown -R web1:client1 /var/www/clients/client1/web1/web/
find /var/www/clients/client1/web1/web -type d -exec chmod 755 {} ;
find /var/www/clients/client1/web1/web -type f -exec chmod 644 {} ;

403 Forbidden Error

• Check directory index file exists
• Verify directory permissions
• Check .htaccess deny rules
• Verify IP restrictions

404 Not Found

• Verify file exists in correct location
• Check case sensitivity (Linux is case-sensitive)
• Verify rewrite rules
• Check document root setting

Email Problems

Cannot Send Email

Cannot Receive Email

• Check MX records point to correct server
• Verify mailbox exists and is active
• Check disk quota not exceeded
• Review spam filter settings
• Check mail logs for errors

# Check mail logs
tail -f /var/log/mail.log

# Test SMTP connection
telnet localhost 25

# Check mail queue
mailq

# Verify MX records
dig MX yourdomain.com

Email Going to Spam

• Configure SPF, DKIM, and DMARC records
• Check server IP reputation
• Avoid spam trigger words
• Ensure PTR record is set
• Test with mail-tester.com

Database Issues

Cannot Connect to Database

# Check MySQL is running
systemctl status mysql

# Test connection
mysql -u username -p

# Check error log
tail -f /var/log/mysql/error.log

# Verify credentials
grep DB_NAME /var/www/clients/client1/web1/web/wp-config.php

Database Performance Issues

• Optimize tables regularly
• Check slow query log
• Increase buffer pool size
• Add indexes to slow queries
• Monitor connections

FTP Connection Problems

FTP Connection Refused

1. Verify FTP service is running:

   systemctl status pure-ftpd-mysql

2. Check firewall allows port 21
3. Verify FTP user is active in ISPConfig
4. Test with different FTP client

FTP Passive Mode Issues

# Configure passive ports
echo "40000 50000" > /etc/pure-ftpd/conf/PassivePortRange

# Restart FTP
systemctl restart pure-ftpd-mysql

# Open firewall ports
ufw allow 40000:50000/tcp

SSL Certificate Issues

Let's Encrypt Renewal Failed

• Verify domain points to server
• Check port 80 is accessible
• Review /var/log/letsencrypt/letsencrypt.log
• Ensure webroot is correct
• Check DNS propagation

# Manual renewal test
certbot renew --dry-run

# Force renewal
certbot renew --force-renewal

# Check certificate
openssl x509 -in /etc/letsencrypt/live/domain.com/cert.pem -text -noout

ISPConfig Access Issues

Cannot Login to ISPConfig

1. Reset admin password:

   mysql -u root -p dbispconfig
   UPDATE sys_user SET passwort = MD5('newpassword') WHERE username = 'admin';
   

2. Check ISPConfig services:

   systemctl status ispconfig

3. Verify port 8080 is open
4. Clear browser cache and cookies

Performance Issues

Slow Website Loading

• Enable caching (opcache, memcached)
• Optimize images
• Enable gzip compression
• Check server load
• Review slow query log
• Consider CDN implementation

# Check server load
top
htop

# Monitor Apache connections
apache2ctl fullstatus

# Check disk I/O
iotop

# Monitor network
iftop

DNS Resolution Issues

Domain Not Resolving

# Check BIND status
systemctl status bind9

# Test DNS resolution
dig @localhost yourdomain.com

# Check zone file syntax
named-checkzone yourdomain.com /etc/bind/pri.yourdomain.com

# Reload DNS zones
rndc reload

Quick Diagnostic Commands

# System resources
free -m
df -h
uptime

# Service status
systemctl status apache2
systemctl status mysql
systemctl status postfix
systemctl status dovecot

# Recent errors
journalctl -xe
dmesg | tail

# Network connections
netstat -tulpn
ss -tulpn

# Process list
ps aux | grep -E 'apache|mysql|php'