I highly doubt that such an old version of CiviCRM would work on a modern version of Joomla. You'll also want to upgrade for security reasons. I would recommend upgrading CiviCRM on Drupal before migrating to Joomla, and your "Unknown Error" will likely disappear.

Also, to troubleshoot the "Unknown Error", turn on debug mode and backtraces: In CiviCRM, please go to Administer menu > System Settings > Debugging and Error Handling, select "Yes" to both "Enable Debugging" and "Display Backtrace", and press "Save". If you're not sure what to do, please update the question with the expanded debugging info.

Demerit is correct about the definer error. See here to fix that error.

I highly doubt that such an old version of CiviCRM would work on a modern version of Joomla. You'll also want to upgrade for security reasons. I would recommend upgrading CiviCRM on Drupal before migrating to Joomla, and your "Unknown Error" will likely disappear.

Also, to troubleshoot the "Unknown Error", turn on debug mode and backtraces: In CiviCRM, please go to Administer menu > System Settings > Debugging and Error Handling, select "Yes" to both "Enable Debugging" and "Display Backtrace", and press "Save". If you're not sure what to do, please update the question with the expanded debugging info.

Demerit is correct about the definer error. See here to fix that error.