Category addition failed (only on one subsite)

Sorry about the delay in response; it’s been a hectic couple of weeks.

Most often when I hear about this problem, it’s because for some reason the DB creation process failed on that subsite, so the required database tables don’t exist. How you fix it somewhat depends on why it happened; which can be difficult to figure out. But a first step is to verify whether or not the My Calendar tables exist on that subsite.

I believe what I did was activate the plugin on the entire network. On creation of a new site, the My Calendar tables are not created.

Well, huh. Nope. I just created another site and those tables seem to have been created. I wonder if there is a way I can trigger the creation of necessary tables for the one site that didn’t have the tables created?

If I Network Deactivate, will My Calendar tables be erased from existing sub-sites?

No, deactivation doesn’t remove tables. Tables are only removed if you delete the plugin and the option to drop tables is enabled in settings.

You can run the function to create tables manually; if you execute mc_upgrade_db() that’ll run all the table creation functions. It needs to be run in the site that has the problem.

I guess I don’t know enough about mc_upgrade_db() to know how best to execute it. add_filter or add_action( ‘init, …)?

So, something like this, in the functions.php file in the theme used by the subsite lacking the tables?

function izzafunction(){

// n === the subsite with no My Calendars tables in place

    if( get_current_blog_id() === n ){
        mc_upgrade_db();
       }
}
add_filter( 'izza_name', 'izzafunction' );

Or should I return mc_upgrade_db();