Critical Issue: Incomplete Update of jDownloads Sub-Plugins Causing Joomla 6 Migration Failure

[tatabdullah]

Dear jDownloads Support Team / Arno,

I am writing to report a critical issue I encountered while attempting to upgrade my site from Joomla 5 to Joomla 6, utilizing jDownloads version 4.1.7.

My site heavily relies on jDownloads, and following your official guidelines, I ensured the main component was updated to version 4.1.7 Stable, which is stated to be Joomla 6 compatible.

However, during the migration preparation, when I disabled the Joomla "System - Backward Compatibility" plugin (which is required for Joomla 6), my site experienced severe fatal errors (specifically, "Class 'JPlugin' not found" Call Stack errors), completely locking me out of both the frontend and the backend admin panel.

After thorough troubleshooting (including checking error logs and database entries), I discovered the root cause:

While the main jDownloads component successfully updated to 4.1.7, several crucial sub-plugins associated with jDownloads remained stuck on older 4.0.x versions and were still attempting to use the deprecated JPlugin class instead of the modern Joomla 5/6 API.

Specifically, the following plugins were not updated alongside the main component and caused the crashes:

    System - jDownloads (remained at v4.0.43)

    Smart Search - jDownloads (remained at v4.0.36)

    Content - jDownloads Tags Correction (remained at v4.0)

To resolve the fatal errors and regain access to my site, I had to completely disable these specific legacy plugins and physically rename the component folders via FTP.

My Request / Question:
Is there a known issue regarding the update routine not properly triggering the update for these sub-plugins to their 4.1.x equivalents? To safely proceed with my Joomla 6 upgrade, what is the official recommended method to ensure these specific sub-plugins (especially the System plugin) are brought up to the Joomla 6 compatible standards without losing my existing download data and configurations?

Thank you for your time and for this excellent component. I look forward to your guidance.

Best regards,
Abdullah Tat

[ColinM]

Abdullah,
Thank you for the query. I have not come across this previously. As far as I know the update to jD4.1.7 went smoothly so I am a little puzzled you had a 'problem'. In particular if the System plugin failed then that would cause very strange results.
From which version were you updating?
Best wishes
ColinM

[Arno]

Hi Abdullah,
thank you for your report.

jDownloads 4.1.x supports Joomla 5 and Joomla 6, and no longer uses the obsolete `JPlugin` class. Consequently, it does not use the plugins mentioned, which are included in the package. 

The plugin versions you listed (`4.0.43`, `4.0.36` and `4.0`) are their current individual version numbers. They do not need to match the component version, so these numbers alone do not indicate an incomplete update.

An outdated third-party plugin could cause this error, even when it appears during a jDownloads operation. We have seen this before: the cause in this topic was the unrelated Textman content plugin.

However, we need the exact error details before identifying the cause on your site. Please provide:

- The full error message and stack trace, especially the file path and line number where `JPlugin` is referenced.
- Your exact Joomla and PHP versions.
- The jDownloads version you upgraded from, and any installation warnings.

If necessary, reproduce this on a backed-up test copy with Debug System enabled and Error Reporting set to Maximum. Restore those settings afterwards, and remove any credentials or other sensitive information before posting the trace.

Please do not uninstall jDownloads or delete its data as a troubleshooting step. Once we know which file causes the error, we can recommend a targeted solution.

Best regards
Arno