Error Log Troubleshooting

Learning Focus

By the end of this lesson you will know how to read error log entries, recognize common patterns, and use logs to diagnose issues.

Log Location and Basic Commands

# View the most recent entries
tail -50 /usr/local/lsws/logs/error.log

# Follow the log in real time
tail -f /usr/local/lsws/logs/error.log

# Search for specific error patterns
grep -i "error\|failed\|denied" /usr/local/lsws/logs/error.log | tail -20

Common Error Patterns

Log Pattern	Meaning	Likely Cause
Failed to start external app	PHP cannot start	Wrong command path or permissions
Connection refused	Socket/port issue	PHP not running or wrong socket
Permission denied	File access blocked	Wrong ownership or permissions
SSL_CTX_use_certificate_chain_file failed	Certificate error	Wrong cert path or format
Max connections reached	Worker pool exhausted	Increase max connections or optimize

Reading a Log Entry

A typical error line includes:

[ERROR] [192.168.1.1] [APVH_example] Failed to connect to socket ...

Part	Meaning
[ERROR]	Severity level
[192.168.1.1]	Client IP (if applicable)
[APVH_example]	Virtual host or component name
Rest of line	Specific error description

Key Takeaways

• The error log is your primary diagnostic tool — learn to read it quickly.
• Use tail -f for real-time monitoring during troubleshooting.
• Common patterns often point directly to the fix.

What's Next

• Return to the Logging and Monitoring module for the complete overview.