This modification will allow most extensions that have not been updated specifically for OpenCart 2.3 to run without needing to be updated. It is guaranteed to work with all Clear Thinking extensions, and is included with any purchase of a Clear Thinking extension.
Both vQmod and ocMod versions of the modification are included. You can choose which to use once you unzip the .zip file. As a bonus, it also includes these improvements for the admin Extensions area:
Fixes the missing the extension links in the left-hand Extensions menu.
Hides duplicate extension names if old extensions still exist.
Properly sorts extensions by name rather than code.
Fixes extensions being disabled when old extension sub-area URLs are visited (for installations that upgraded from an older OpenCart version).
Note: Extensions must be compatible with OpenCart 2.2 in order for them to work on 2.3. I can't guarantee the modification will work with ALL extensions, but if you have issues with an extension when it is enabled, please contact me and I'll take a look.