A Practical Moodle Troubleshooting Workflow

Summary: This guide lays out a practical Moodle troubleshooting workflow, including symptom capture, log inspection, X-Sendfile validation, PHP-FPM sizing, timeout analysis, and common hidden configuration issues.

This is the structured response for “the site is broken or slow” when you need to move from symptoms to a real root cause instead of changing random settings.

Step 1: Write down the symptom precisely

Do not begin with theory. Begin with a reproducible statement:

• course creation takes 40 seconds
• large downloads fail
• grading triggers a timeout
• welcome emails show the wrong sender name

This matters because different symptom classes point to different layers immediately.

Step 2: Confirm access to the right systems

You should have access to:

• Moodle admin
• the web server
• PHP-FPM configuration and status pages if available
• database access or monitoring
• logs for the relevant time window

If you cannot inspect all those layers, troubleshooting becomes speculation very quickly.

Step 3: Check recent changes first

Before tuning anything, ask what changed recently:

• plugin deployment
• upgrade
• PHP version change
• database import
• web server config edit
• traffic spike

The most efficient fixes often come from correlating the failure to a recent change rather than from deep system analysis.

Step 4: Validate large-file delivery separately

If the problem involves large files, check file delivery as its own subsystem. The SOP explicitly covers Apache mod_xsendfile as a common performance and reliability fix.

The sequence is:

1. confirm mod_xsendfile is installed
2. add the required Apache directives to the vhost
3. enable the corresponding Moodle setting
4. test both a direct Apache file and a Moodle-served file

This is one of the fastest ways to resolve “large downloads are slow or broken” without rewriting application code.

Step 5: Check PHP-FPM sizing before blaming Moodle

Many “Moodle is slow” complaints are really PHP-FPM pool exhaustion. Look for:

• max children warnings
• request queueing
• under-sized pools relative to available RAM
• multiple sites sharing the same pool or server resources poorly

The SOP specifically calls out checking the pool configuration and status pages rather than guessing at values.

Step 6: Separate timeout types by layer

Timeouts do not all mean the same thing. Distinguish between:

• Apache or FastCGI read timeouts
• Varnish or proxy timeouts
• MySQL connection timeout or dropped connection
• application-side slowness due to expensive queries or blocked PHP workers

Increasing every timeout value without identifying the failing layer usually just hides the real problem.

Step 7: Look for configuration mistakes that are easy to miss

The SOP includes several issues that are easy to overlook because they are small:

• spaces or stray output in PHP files
• wrong sender-name configuration for welcome emails
• CLI PHP version not matching the web PHP version
• environment-specific performance regressions such as the ICM course-creation case study

These often explain “we only changed something small” incidents.

Step 8: Close the loop after the fix

When the issue is resolved, document:

• what failed
• why it failed
• what fixed it
• what should be monitored or changed to prevent recurrence

If you skip this, you will eventually rediscover the same incident under a different name.

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Solin specializes in Moodle troubleshooting, performance analysis, and production incident recovery. Need help? Contact us.