A 500 error on PrestaShop can cost sales every minute. The cause is often a faulty module, permissions problem, or failed update. Here's how to react quickly.
Symptoms
- White page or 500 error on front or back-office
- Error after installing a module
- Problem after a PrestaShop update
- Checkout that no longer works
Common Causes
- Incompatible module: A third-party module poorly coded or incompatible with your version.
- Conflicting override: Multiple modules overriding the same class.
- File permissions: Bad permissions on cache/ or var/ folders.
Diagnostic Steps
- Enable debug mode in config/defines.inc.php
- Disable recently installed modules via DB
- Delete cache (var/cache/) and regenerate
- Check PHP logs and PrestaShop logs
Automate with MoniTao
MoniTao protects your e-commerce:
- Immediate detection of 500 errors
- Checkout monitoring (critical endpoint)
- SMS alerts to react even at night
Best Practices
- Always test modules on a staging environment
- Make a complete backup before every update
- Use maintenance mode during updates
- Monitor critical endpoints: home, category, product, checkout
FAQ
How to enable PrestaShop debug mode?
In config/defines.inc.php: define('_PS_MODE_DEV_', true);
How to disable a module without the back-office?
In the ps_module table, set active = 0 for the concerned module.
What permissions for folders?
755 for folders, 644 for files. var/ and cache/ in 777 if needed.
Does MoniTao monitor checkout?
Yes, create a specific monitor for the cart or order page.
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