TYPO3 error messages: complete troubleshooting guide

TYPO3 is an enterprise CMS widely used for large websites. In this guide, we cover the most common TYPO3 errors.

1. Oops, an error occurred!

Symptom

TYPO3 default error page appears.

Cause

• PHP exception
• Database error
• Configuration issue

Solution

1. Enable debug - In LocalConfiguration.php or Install Tool
2. View var/log/ - system.log and exception.log
3. Check typo3temp/ - Must be writable
4. Clear cache - Via Install Tool > Maintenance

2. Backend login issues

Symptom

Cannot login to TYPO3 backend.

Cause

• Wrong password
• Backend locked
• Session problem
• Browser cache

Solution

1. Reset password - Via Install Tool
2. Clear be_sessions - In database
3. Check lock file - LOCK_BACKEND in typo3conf/
4. Clear browser cookies - For the domain

3. Install Tool locked

Symptom

Access denied to Install Tool.

Cause

• ENABLE_INSTALL_TOOL file missing
• File expired (1 hour valid)
• Permissions problem

Solution

1. Create file - typo3conf/ENABLE_INSTALL_TOOL (empty)
2. Check permissions - Must be readable by webserver
3. Renew within 1 hour - File expires automatically
4. Via TYPO3 Console - typo3 install:lock 0

4. Cache related errors

Symptom

Frontend shows old content or crashes.

Cause

• Cache corrupt
• Insufficient disk space
• Redis/Memcached offline

Solution

1. Clear all caches - Install Tool > Maintenance > Flush cache
2. Remove typo3temp/ - Manually via FTP
3. Check cache backend - In LocalConfiguration.php
4. Restore default cache - FileBackend

5. Class not found errors

Symptom

Fatal error: Class X not found.

Cause

• Autoloader not updated
• Extension removed but still configured
• Composer dependencies

Solution

1. Dump autoload - composer dump-autoload
2. Remove extension config - In PackageStates.php
3. Clear opcache - In PHP settings
4. Reinstall extension - Via Extension Manager

6. Database connection errors

Symptom

Cannot connect to database.

Cause

• MySQL offline
• Credentials changed
• Socket problem

Solution

1. Check LocalConfiguration.php - Database array
2. Test connection - Via phpMyAdmin
3. Update via Install Tool - Database wizard
4. Check socket path - In MySQL config

7. Maximum execution time exceeded

Symptom

Timeout during backend operations.

Cause

• PHP time limit too low
• Large data processing
• Import/export

Solution

1. Increase time limit - max_execution_time = 240
2. Use CLI - typo3 console commands
3. Split tasks - Into smaller batches
4. Use Scheduler - For background tasks

8. Extension conflict errors

Symptom

Site crashes after extension update.

Cause

• TYPO3 version incompatibility
• Extension dependencies
• Breaking changes

Solution

1. Check compatibility - In ext_emconf.php
2. Rename extension folder - In typo3conf/ext/
3. View extension changelog - For breaking changes
4. Rollback via backup

9. File not found (FAL errors)

Symptom

Images or files not visible.

Cause

• File deleted
• Storage configuration
• Permissions problem

Solution

1. Check File > Filelist - Does file exist?
2. Verify storage - File > File Storage
3. Check permissions - fileadmin/ must be accessible
4. Regenerate thumbnails - Via Install Tool

10. Scheduler task failures

Symptom

Scheduled tasks not executing.

Cause

• Cron not configured
• Task exception
• Insufficient permissions

Solution

1. Check cron - /usr/bin/php typo3/sysext/core/bin/typo3 scheduler:run
2. View scheduler module - In backend
3. Check task log - For exceptions
4. Reactivate task - Disable/enable

TYPO3 troubleshooting tips

• Use Install Tool - For maintenance tasks
• View logs - var/log/ contains all errors
• CLI tools - More powerful than backend
• Test on staging - Before production updates

Related articles

• TYPO3 hosting - Best TYPO3 hosting
• TYPO3 hub - Everything about TYPO3
• 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.