Custom Taxonomies Not Working in WP 3.1

Same thing is happening to me.

I have just upgraded to WP 3.1 and my custom taxonomies are no longer behaving correctly.

1. When I go to click on my custom taxonomy in the admin, I receive the WP ‘Cheatin’ uh?’ Error.

2. My WPQuery no longer filters to specific taxonomy slugs.

Registering my custom taxonomy like so:

add_action( 'init', 'build_taxonomies', 0 );
 function build_taxonomies() {
    register_taxonomy(
	    'product_Category',
	    'products',
	    array(
	        'hierarchical' => true,
	        'label' => 'Product Category',
			'public' => true
	    )
	);
}

Have been calling my query like so:

<?php $args = array( 'post_type' => 'products', 'posts_per_page' => 10, 'taxonomy' => 'private-label' ); ?>

				<?php $loop = new WP_Query( $args ); ?>
				<?php while ( $loop->have_posts() ) : $loop->the_post(); ?>

….etc…..

Anybody have any ideas what’s different about the way WP 3.1 handles custom taxonomies?

Thanks for the capital letter tip!

Changing my taxonomy name to be lowercase both of my issues.

Unfortunately though, in changing the original taxonomy name, it broke my nav_menu set up that was using the same taxonomy, giving me this error:
Catchable fatal error: Object of class WP_Error could not be converted to string in /home/---/---/wp-includes/formatting.php on line 445

Have investigated: this is a bug. Apparently it happens any time you change your custom taxonomy name. Some people had success deleting certain things in phpmyadmin. I decided to a fresh install.

Now everything is back to normal (minus some content that I now need to re-enter) and working perfectly.

Good luck!

Just a note – I just discovered that it also cannot contain any spaces!

thx!