The most common cause of this issue is that the Currency Switcher has been installed in a directory whose name is not "woocommerce-aelia-currencyswitcher". Due to WordPress architecture, to check if a plugin is enabled, it's necessary to look for it using its full path and file name. Even though the Currency Switcher is actually enabled, if the path doesn't match, then the add-on won't be able to find it.
If you installed the Currency Switcher in a folder with a name different from woocommerce-aelia-currencyswitcher, simply follow the instructions below:
- Disable the Currency Switcher.
- Rename the Currency Switcher folder to woocommerce-aelia-currencyswitcher.
- Enable the Currency Switcher.
- Enable the add-on that was throwing the error.