Drupal error messages: complete troubleshooting guide

Drupal is a professional CMS widely used for complex websites. In this guide, we cover the most common Drupal errors.

1. White Screen of Death (WSOD)

Symptom

Website shows only a white screen.

Cause

• PHP fatal error
• Module conflict
• Memory limit

Solution

1. Enable error display - In settings.php: $config["system.logging"]["error_level"] = "verbose";
2. Check PHP error log - In hosting panel
3. Rename problem module - In /modules/
4. Increase PHP memory - memory_limit = 256M

2. The website encountered an unexpected error

Symptom

Drupal shows generic error message.

Cause

• Database error
• Module exception
• Configuration issue

Solution

1. View dblog - /admin/reports/dblog
2. Check sites/default/files/logs - If available
3. Drush watchdog-show - Via command line
4. Restore from backup - If needed

3. PDOException: SQLSTATE connection error

Symptom

Database connection failed.

Cause

• MySQL server offline
• Wrong credentials
• Database corrupt

Solution

1. Check settings.php - Verify database array
2. Test MySQL connection - Via phpMyAdmin
3. Repair database - mysqlcheck --repair
4. Contact hosting - For server problems

4. EntityStorageException

Symptom

Error when saving content or configuration.

Cause

• Database table problem
• Entity field conflict
• Update hook failed

Solution

1. Drush entity-updates - drush entity:updates
2. Clear cache - drush cr
3. Database update - drush updb
4. Check fields - In /admin/structure/types/

5. The requested page could not be found (404)

Symptom

Pages give 404 after update or migration.

Cause

• Path alias problem
• .htaccess missing
• Clean URLs disabled

Solution

1. Clear cache - drush cr
2. Regenerate aliases - /admin/config/search/path
3. Check .htaccess - Must be present
4. Check URL settings - In performance settings

6. Access denied

Symptom

Access denied to page or function.

Cause

• User permissions
• Role permissions
• Node access

Solution

1. Check user role - /admin/people/permissions
2. Check content permissions - Per content type
3. Drush user-login - Direct admin access
4. Rebuild permissions - drush php-eval "node_access_rebuild()"

7. Maximum execution time exceeded

Symptom

Timeout during cache rebuild or updates.

Cause

• PHP time limit too low
• Heavy operation
• Processing lots of content

Solution

1. Increase time limit - max_execution_time = 300
2. Use Drush - No browser timeout
3. Split operations - Into batches
4. Temporarily disable modules

8. Allowed memory size exhausted

Symptom

PHP memory exhausted.

Cause

• Views with lots of data
• Image processing
• Module memory leak

Solution

1. Increase memory_limit - 256M or more
2. Optimize Views - Use paging
3. Check contrib modules - Memory intensive?
4. Enable caching - Drupal cache configuration

9. Twig template error

Symptom

Frontend shows template error.

Cause

• Syntax error in template
• Variable not available
• Theme compatibility

Solution

1. Check template file - Mentioned line number
2. Compare with original - Copy from core/contrib
3. Enable Twig debugging - In services.yml
4. Clear cache - After template fix

10. Module conflict errors

Symptom

Site crashes after module installation.

Cause

• Incompatible module version
• Missing dependencies
• API changes

Solution

1. Rename module folder - Via FTP/SFTP
2. Drush pm-uninstall - If CLI access works
3. Check module dependencies - In .info.yml
4. Update Drupal core - For compatibility

Drupal troubleshooting tips

• Use Drush - More powerful than web interface
• Read dblog - Most errors are here
• Make backups - Files and database
• Test on Dev - Before production updates

Related articles

• Drupal hosting - Best Drupal hosting
• Drupal hub - Everything about Drupal
• HTTP 500 error explained - Server errors

Frequently Asked Questions

How long does it take to implement this?

Implementation time varies per situation. Simple configurations can be done within an hour, more complex setups may take several hours to a day.

What are the costs?

Costs depend on your hosting provider and package. Many basic features are included for free, advanced features may incur additional costs.

Do I need technical knowledge?

You need little technical knowledge for the basics. Most hosting providers offer extensive documentation and support to help you.