Important: Please try this on a test site first!

• Have JCal Pro version 4.5.4 installed on your Joomla 3 site.
• Disable your "Content - JCal Pro", "System - JCal Pro", and "User - JCal Pro" plugins.
• Upgrade your Joomla 3 site to Joomla 5.
• Visit the Extensions Update screen. You will find a warning notifying you that you have JCal Pro 5.0.0 available for upgrade. Upgrade JCal Pro 4.5.4 to 5.0.0.
• Check the disabled JCal Pro plugins. You will find that they have been automatically re-enabled on the update.