This sounds like the file /youradmin/includes/modules/update_product.php either didn't get modified during the install/update, or perhaps it was modified or replaced by another add-on that you've installed?
The 1st thing to do is navigate you way to the shipping module settings, click the button to uninstall ozpost, then click again to re-install. Most (if not all) of your current settings will be retained during this process.
The ozpost installation code will attempt to (re)modify the files it needs to function and all should be good. It will generate warnings about any files can't be updated (which would typically be caused if the file or folder permissions are too restrictive).
Please let me know if you still have the problem after doing this because if it is caused from changes made to the file(s) by another module it may require a manual approach to merge the changes. We'll cross that bridge if we come to it.
Cheers
RodG
Bookmarks