Ticket #50324: plugin-reproduce-50324.php

<?php
// Plugin: Reproduce error "Error: Could not retrieve site data."
// Description: With plugin, cannot create new blogs in multisite

add_action( 'clean_site_cache', function() {
        update_site_option( 'insert_id_test' . time() , true );
});

add_action( 'wp_initialize_site', function( $site ) {
        // Anything in here will happen on the wrong site
} );