Normally, only the super admin is able to activate plugins on the child theme. So a ‘normal’ administrator is not able to activate plugins. I found some fixes on the web, but they all came with a few security issues. An example, give all the normal administrators the role of network admin and hide the additional ‘network’ menu items. To me this is not a real solution. So I made a plugin / script (just how you use it) that allows normal administrators to activate plugins without any weird side-effects.
This script hooks onto the user_has_cap filter and checks if the current user is an administrator. It this is the case, the supplied capabilities are matched with the ones we want to enable for normal administrators (‘manage_network_plugins & ‘activate_plugins’), and these are set to true. That’s it. The neat thing is, only the capabilites that are in the array are enabled and you don’t get any security issues or whatever. So you can even add more capabilities if you want to.
The code is below. Copy the code and place it in a file in the wp-content/mu-plugins/ folder. Create this folder if it does not exists. Do not place it in a subfolder. Files in this folder are automatically loaded for every site and don’t show in the plugin list. Please leave me a note if this helped you, good luck!!