I am getting the same alert too!
Try the “regenerate the thumbnails” button. Worked for me, but doesn’t quite fix the problem.
OK so I found a work-around that has yet to fail.
Open scissors-watermark/functions.php and comment out ln1139 – 1155. So this function is no longer used:
// Check if exists files of custom sizes. If not we re-create all sizes including custom sizes.
if ( !empty( $_wp_additional_image_sizes ) )
{
$custom_sizes = array_keys( $_wp_additional_image_sizes );
if ( in_array( $_POST['target'], $custom_sizes ) ):
// TODO: It re-create all sizes. It should to make only the custom size which miss
$attachment_metadata = get_post_meta($post->ID, '_wp_attachment_metadata');
$new_metadata = wp_generate_attachment_metadata( $post->ID, $fullfile );
if ( !wp_update_attachment_metadata( $post->ID, $new_metadata ) ):
return __('Can not update attachment metadata.', 'scissors');
endif;
endif;
}
Whatever this was doing was failing, and since disabling it I have been able to use the plugin like expected.
Cheers!
