Install and reinstall are where this plugin does its work. Updates to OSCampus undo the patch until you reinstall Compat.
Confirm OSCampus appears under administrator Components. Open System → Install → Extensions and upload the Compat ZIP. Enable the plugin when needed. Read install messaging for patch success or failure.
Install the newer ZIP over the existing plugin from https://recreatinganew.com. Read the install message again. Retest lesson create and edit.
Update OSCampus as its vendor documents. Reinstall RCA OSCampus Compat so the AbstractBase patch applies again. Confirm lesson edit still works. Confirm AbstractBase.php.rca-orig is still present unless you intentionally removed it. Clear opcode cache if lesson edit still fatals immediately after reinstall.
Open System → Manage → Extensions and uninstall System - RCA OSCampus Compat. Read the uninstall message. When restore succeeds, AbstractBase.php is copied back from AbstractBase.php.rca-orig. When the message says the backup was missing, restore OSCampus from your site backup or reinstall stock OSCampus.
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