PrestaShop Restoration Failures & 500 Errors on OVH: A Community Debugging Guide

PrestaShop Restoration Woes: Debugging 500 Errors and OVH Hosting Challenges

A PrestaShop merchant, jeanmiche35, faced a critical situation after an OVH-initiated restoration of their PrestaShop 1.6.1.20 store went awry. The initial restoration, intended to fix an email notification issue, resulted in a functional homepage but blank pages or 500 errors when navigating product links. A subsequent manual FTP restoration attempt, where the user intentionally left the /cache/smarty/cache and /cache/smarty/compile folders untouched, catastrophically rendered the entire site unavailable. This thread delves into the community's swift and comprehensive advice to bring the shop back online and address underlying issues.

The Initial Crisis and Debugging Hurdles

The core problem was a non-functional PrestaShop site displaying 500 errors, even after attempts to enable debug mode. The user initially mistyped the debug file as define.inc.php instead of defines.inc.php. Even after correcting this, the 500 errors persisted without any specific error messages, indicating a problem occurring before PHP could execute and display debug information.

A significant challenge highlighted was the sheer volume of files within the Smarty cache directories (/cache/smarty/cache and /cache/smarty/compile). The user reported that clearing these via FTP could take up to two days, making quick troubleshooting difficult.

Key Troubleshooting Steps and Solutions

1. Backup Before Action: The first crucial advice from Knowband Plugins was to always back up the current state (files and database), even if broken, before attempting any further restorations or modifications.
2. Correct Debug Mode Activation: Ensure the correct file /config/defines.inc.php is modified to set _PS_MODE_DEV_ to true.
3. Efficient Smarty Cache Clearing: For hosts like OVH that offer SSH access, Knowband Plugins provided invaluable commands to quickly clear the massive Smarty cache without affecting index.php files:

   find cache/smarty/compile -type f ! -name index.php -delete
   find cache/smarty/cache -type f ! -name index.php -delete

   This bypasses the slow FTP process by executing deletions directly on the server.

4. Investigating .htaccess: When 500 errors persist despite debug mode being active, the .htaccess file is a prime suspect. Eolia and Knowband Plugins suggested renaming the .htaccess file (e.g., to .htaccess.bak). An error in this file can prevent Apache from even reaching PHP, thus suppressing debug messages.
5. Regenerating .htaccess: After renaming, if the site shows "NOT FOUND", Knowband Plugins advised testing a non-rewritten URL (e.g., yourdomain.com/index.php?c>). If this works, log into the PrestaShop back office (yourdomain.com/admin/index.php), navigate to Shop Parameters > Traffic & SEO, and simply save the settings. PrestaShop will then regenerate a fresh, correct .htaccess file.
6. OVH Specifics for Email: The original reason for the restoration attempt was email notification failure. Eolia and Knowband Plugins clarified that for OVH hosting, only SMTP mode works reliably for sending emails from PrestaShop. This needs to be configured in Advanced Parameters > E-mail using OVH mail account credentials.

Resolution and Key Takeaways

Ultimately, jeanmiche35 managed to restore their site by performing a manual FTP restoration: deleting all existing files and folders on the OVH server except the smarty folder, and then uploading a 15-day old backup. This suggests the primary issue was file corruption or an incomplete/faulty restoration affecting core PrestaShop files, and the Smarty cache itself wasn't the direct cause of the site being down, but rather a symptom of a larger problem. The community's guidance on debugging and specific OVH considerations was instrumental in reaching this resolution.

This thread underscores several critical lessons for PrestaShop merchants and developers:

• OVH's automated restoration processes may not always be compatible with PrestaShop, especially for complex issues.
• Always enable debug mode correctly and understand its limitations (e.g., .htaccess errors bypassing PHP).
• Efficiently managing and clearing the Smarty cache is vital for troubleshooting and performance.
• .htaccess can be a silent killer for site functionality; knowing how to troubleshoot and regenerate it is crucial.
• Hosting-specific configurations (like OVH's SMTP requirement for emails) must be understood and applied.
• Manual backups and a clear understanding of what you're restoring (files vs. database) are paramount.