A 500 Internal Server Error (HTTP Error 500) is one of the most frustrating issues faced by online store owners. Unlike 404 or 403 errors, it doesn’t clearly explain the cause and often appears suddenly — the website just stops working.
If you run a PrestaShop store, this error can indicate anything from a minor code issue to a serious server failure. In this article, we’ll break down what this error is, why it happens, and how to properly diagnose and fix it.
What Does Error 500 Mean
A 500 error is a generic server response that means:
“The server encountered a problem and cannot process the request”
It’s important to understand:
this is not a browser or user error — the issue is always on the server side or within the application (your store).
How the Error Appears
It may look different depending on the case:
500 Internal Server Error- White screen (White Screen of Death)
- Hosting provider’s custom error page
- Completely blank page
In PrestaShop, the most common case is the white screen, which makes debugging harder.
Main Causes of Error 500 in an Online Store
1. PHP Code Errors
The most common reason:
- syntax errors
- calling undefined methods
- PHP version incompatibility
- errors in custom modules
Example:
Call to undefined method
2. Issues with PrestaShop Modules
After:
- installing a new module
- updating a module
- manually deleting files
conflicts may occur.
Most commonly affected:
- override classes
- hooks
- class autoloading
3. Incorrect File Permissions
If files or directories have incorrect permissions:
- the server cannot read files
- or cannot execute scripts
Standard:
- folders:
755 - files:
644
4. Errors in .htaccess
The .htaccess file controls routing and server rules.
Errors may appear after:
- enabling SEO-friendly URLs
- manual editing
- site migration
5. Server Limitations
Hosting may terminate script execution due to:
- insufficient memory (
memory_limit) - long execution time (
max_execution_time) - CPU limits
6. Database Errors
For example:
- corrupted tables
- invalid queries
- structure incompatibility
7. PrestaShop Update Issues
After updating the core:
- old modules may break
- override files may conflict
- database structure may change
How to Find the Cause of Error 500
Step 1. Enable Error Display
If you have access to the PrestaShop admin panel, the easiest way is to enable debug mode:
Go to:
Advanced Parameters → Performance
Enable Debug Mode.
If the admin panel is not accessible (for example, the site is completely down), use the code method.
In PrestaShop:
Open the file:
/config/defines.inc.php
Find the line:
define('_PS_MODE_DEV_', false);
Change it to:
define('_PS_MODE_DEV_', true);
After that, instead of a white screen, you will see the actual error.
Step 2. Check Server Logs
Logs are the most reliable source of information.
Where to look:
/var/log/apache2/error.log/var/log/nginx/error.log- hosting control panel logs
They will show the exact cause of the error.
Step 3. Check Recent Changes
Ask yourself:
- Was a module installed?
- Was PrestaShop updated?
- Was code modified?
If yes — roll back the changes.
Step 4. Disable Modules
If the admin panel is not accessible:
- Go to
/modules/ - Rename the suspicious module
Example:
mymodule → mymodule_off
Step 5. Regenerate .htaccess
Delete the .htaccess file and generate a new one:
In admin panel:
Shop Parameters → Traffic & SEO → Save
Step 6. Check PHP Version
A common issue:
- old module + new PHP (e.g., 8.2)
- or vice versa
Recommendation:
- PrestaShop 1.7 → PHP 7.4
- PrestaShop 8 → PHP 8.1+
Step 7. Check File Permissions
Make sure:
/var/www/public_html → 755
files → 644
Common Real-World Cases
Case 1: White screen after installing a module
Cause: override error
Solution: clear /override/ and clear cache
Case 2: Error after update
Cause: module incompatibility
Solution: disable third-party modules
Case 3: Error only on frontend
Cause: theme issue
Solution: switch to the default theme
Case 4: Error during checkout
Cause: payment module failure
Solution: check logs and API
How to Prevent Error 500
1. Make Backups
Before any changes:
- files
- database
2. Check Compatibility
Before installing a module, verify:
- PrestaShop version
- PHP version
3. Minimize Overrides
The fewer overrides — the more stable the system.
4. Monitoring
Use:
- uptime monitoring
- error logging
- maintenance services
We provide a platform for your store that monitors uptime, cleans the system, blocks bots, and more:
https://ewonta.shop/ru/podderzhka-internet-magazinov
If you encounter an error and cannot fix it yourself — contact us, we’ll help.
Support >
