Lost Sight of Extensions In Admin Functions After Reverting

I tried, and failed, to upgrade from 1.5.6.4 to 3.0.2 due to error messages. I have successfully reverted to version 1.5.6.4 and the system is working OK including all the various modules and extensions.
However, in the administration activities the options under the Extensions tab have ceased to show any of the installed or available modules and all I get is an error message "The page you are looking for could not be found! Please contact your administrator if the problem persists."
As an example that generates this error the web address shows "(site)/admin/index.php?route=extension/module&token=d068b4fc657dd90402eb3282c8537462".
I would appreciate some guidance on how to make the various extensions visible again so I can edit or amend any of them.
Thanks, John

OpenCart 1.5.6 can't load extensions from sub-directories, which is why you get that message. For example, if you load the extension/module page, it's trying to load from the directory instead of the file, so it doesn't find anything. You can fix it by removing the sub-directories in this directory:

/admin/controller/extension/

For example, delete or rename this directory:

/admin/controller/extension/module/
to
/admin/controller/extension/module-delete/

Just keep in mind you'll lose any extensions in that directory if you actually delete it, so if there are files you want to save in there, make sure you rename it.

Thank you Johnathan. That has restored them.
I had to do the same change with the extension/feed, payment, shipping, & total sub-directories as well.
I also checked the backup I took before attempting the upgrade and the these sub-directories weren't there. Would the upgrade process to 3.0.2 have created them?
John

Yes, later versions of OpenCart use sub-directories for extensions, which can cause this issue when reverting back. Not many people do that process (they usually just scrap the new installation since it's often separate), so it's not a common issue, but it's something I've seen before when working with extensions for different OpenCart versions.

If you do the same upgrade-revert process in the future, you'll need to make sure to do this step as well. It's one reason I'd suggest using a separate installation for your upgrade first, so you can test everything out and make sure it's working right.