When WordPress is being upgraded to a new release, a database lock is employed which limits any other update process from launching.
The database lock should be removed automatically once the platform update is finished, but if you find that the error keeps happening, you can manually lift the lock. The simplest method is to download and install the Fix Another Update in Progress plugin.
Log into the WordPress administration dashboard and select Plugins > Add New. Search for Fix Another Update, then install and activate the plugin.
Navigate to Settings > Fix Another Update In Progress and the database lock will be removed.
If you wish to remove the lock directly in the database, first log into cPanel Account. Select Databases > phpMyAdmin from the cPanel menu.
Select your WordPress database from the sidebar, then click the Browse button next to the wp_options database table (your database prefix may be different).
In the database rows that appear, look for an entry called ‘core_updater.lock’ and select the Delete button to remove. You can now proceed with your outstanding updates.