If you are maintaining or migrating legacy Joomla sites built with SEBLOD, you know that it is a powerful beast. But its strength—complexity—is also its biggest pain point during upgrades.

I recently worked on a major migration project (moving a heavy SEBLOD site to Joomla 4/5) and hit a wall. The file system was updated, but the site was throwing critical database errors on both the backend and frontend.

If you are stuck with "Unknown column" errors during a SEBLOD update, this guide documents the exact fix.

The Scenario

We were migrating a production site heavily dependent on SEBLOD and its ecosystem of Add-ons. As part of the modernization process, I attempted to update the SEBLOD Toolbox Add-on to the latest version compatible with modern Joomla.

That is when the migration halted.

The Errors

Two specific errors appeared that stopped us in our tracks.

1. Backend Error (During Add-on Installation)

When attempting to install/update the Toolbox Add-on, Joomla threw this error:

Unknown column 'params' in 'field list'

2. Frontend Error (Search Forms)

Simultaneously, the search forms on the frontend—which relied on SEBLOD’s search & list types—crashed with a fatal error:

Fatal error: Unknown column 'a.storage_key'

The Root Cause

After some digging (and finding a related discussion on GitHub), the issue became clear: Database Schema Drift.

At some point in the site's history, previous automatic updates had failed silently. While the SEBLOD files were updated to newer versions, the database structure had not evolved with them. The PHP code was looking for columns (params, storage_key) that simply didn't exist in the database tables.

The auto-updater couldn't fix this because it assumed the database was already at a specific version state.

The Fix: Replaying the SQL Updates

To resolve this, I had to manually synchronize the database schema by "replaying" the missed updates. Instead of guessing which columns were missing, I applied the official SQL updates in sequence. Here is the procedure:

Step 1: The Safety Net

Before running any queries, backup your database. We are applying structural changes, so having a restore point is non-negotiable. I performed these tests on a staging environment first.

Step 2: Identify the Legacy Version

I checked the original Joomla 3 site to determine the exact version of SEBLOD that was previously running. This gave me my "starting point."

Step 3: Locate the SQL Update Files

I downloaded the latest SEBLOD installation package and extracted it locally. I navigated to the SQL update folder (usually /extensions/com_cck/admin/install/upgrades). This folder contains a chronological list of .sql files (e.g., 3.18.0.sql, 3.19.0.sql, etc.).

Step 4: Apply Updates Sequentially

Starting from the version number I identified in Step 2, I took every subsequent .sql update file and ran them in order against the database.

For example: If the site was effectively stuck on version 3.17.5 structure, I manually executed the full content of 3.18.0.sql, then 3.19.0.sql, and so on, up to the current version.

Step 5: Verify & Reinstall

After applying the full update chain on the test environment and verifying there were no SQL syntax errors:

  1. I applied the same SQL stack to the migration site.
  2. I went back to the Joomla backend and re-installed the Toolbox Add-on.

Because the database structure finally matched what the installer expected, the installation completed successfully without the "Unknown column" error.

The Outcome

  • Backend: The Add-on updated successfully and the error log was clean.
  • Frontend: The search forms immediately started working again, as the `storage_key` and other missing columns were properly restored.

Conclusion

When migrating legacy Joomla sites, never assume the database is in sync with the files. If you encounter "Unknown column" errors, the cleanest fix is often to manually re-apply the chain of SQL updates from the vendor's package. It ensures you don't miss any other hidden structural changes.

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