This reference covers frequently-encountered Drupal and Joomla error scenarios and their typical resolutions — a practical troubleshooting companion for these CMS platforms.
Drupal: White Screen of Death (Blank Page, No Error)
tail -f /var/log/apache2/error.logA blank page with no visible error often means PHP fatal errors are occurring but not displayed (display_errors disabled, appropriate for production) — check web server error logs for the actual underlying PHP error.
Drupal: "The website encountered an unexpected error"
drush watchdog:showDrupal's built-in logging (watchdog) often has more specific error detail than the generic user-facing message — check this first for genuine diagnostic information.
Drupal: Database Connection Errors
cat sites/default/settings.php | grep -A 10 databasesVerify database credentials in settings.php are correct and the database service is actually running — a common cause after server migrations or credential rotation without updating this configuration file.
Drupal: Cache-Related Display Issues
drush cache:rebuildMany seemingly odd display issues (outdated content showing, broken layouts after an update) resolve with a cache rebuild — a reasonable first troubleshooting step for many non-obvious Drupal display problems.
Joomla: "JFolder::create: Could Not Create Directory" During Updates/Installs
sudo chown -R www-data:www-data /var/www/joomla
sudo chmod -R 755 /var/www/joomlaFile permission issues are a common cause — verify the web server user has appropriate write permissions to the relevant directories.
Joomla: "Session Data Could Not Be Saved"
Often indicates a database or session storage configuration issue — verify the database is accessible and the sessions table exists/is writable; occasionally caused by disk space exhaustion if session data is file-based.
Both Platforms: "500 Internal Server Error" After an Update
tail -50 /var/log/nginx/error.logCheck web server logs for the specific error — often a PHP version compatibility issue if the update requires a newer PHP version than currently installed, or a module/extension conflict introduced by the update.
Both Platforms: Extremely Slow Page Load
See How to Optimize Performance for Drupal/Joomla on a VPS for systematic performance troubleshooting — check for missing caching configuration, inefficient database queries from a specific module/extension, or genuinely insufficient server resources for your site's traffic.
Both Platforms: Broken After a Third-Party Module/Extension Update
Temporarily disable the specific module/extension to confirm it's genuinely the cause, then check for compatibility notes or known issues with that specific version before re-enabling or seeking an alternative/updated version.
Using Maintenance Mode During Troubleshooting
drush state:set system.maintenance_mode 1Enable maintenance mode while actively troubleshooting a broken site, avoiding visitors encountering the broken state while you diagnose and fix the underlying issue.
Common Errors
Error persists despite trying standard fixes — check for recently changed server-level configuration (PHP version, memory limits, recently applied security patches) that might have inadvertently affected CMS compatibility, not just CMS-level configuration alone.
Continue Reading
- How to Optimize Performance for Drupal/Joomla on a VPS
- How to Back Up and Restore a Drupal/Joomla Site
- Common CMS Migration Pitfalls and How to Avoid Them
Browse more articles in CMS Platforms Beyond WordPress.
