Custom Post Type Archive Template

I think you should add support for custom taxonomy types and name the file taxonomy-cpt-type.php where cpt is the name of your Custom Post Type.

Your CPT archive file should be named archive-cpt.php where cpt is the name of your Custom Post Type.

Here's all the code which has been tested.

Note: You shouldn't be using tag or tags as the name of your custom taxonomy type as it will conflict with existing core functions.

add_action( 'init', 'wpsites_cpt_post_type' ); function wpsites_cpt_post_type() { register_post_type( 'cpt', array( 'labels' => array( 'name' => __( 'CPT', 'theme' ), 'singular_name' => __( 'CPT', 'theme' ), ), 'has_archive' => true, 'hierarchical' => true, 'menu_icon' => true, 'public' => true, 'rewrite' => array( 'slug' => 'cpt', 'with_front' => false ), 'supports' => array( 'title', 'editor', 'author', 'thumbnail', 'excerpt', 'trackbacks', 'custom-fields', 'revisions', 'page-attributes' ), 'taxonomies' => array( 'cpt-type' ), )); } 

And this for registering a Taxonomy Type page where you can create unlimited tax types.

add_action( 'init', 'wpsites_register_taxonomy_types' ); function wpsites_register_taxonomy_types() { register_taxonomy( 'cpt-type', 'cpt', array( 'labels' => array( 'name' => _x( 'Types', 'taxonomy general name', 'theme' ), 'add_new_item' => __( 'Add New CPT Type', 'theme' ), 'new_item_name' => __( 'New CPT Type', 'theme' ), ), 'exclude_from_search' => true, 'has_archive' => true, 'hierarchical' => true, 'rewrite' => array( 'slug' => 'cpt-type', 'with_front' => false ), 'show_ui' => true, 'show_tagcloud' => false, )); } 

Replace all instances of cpt with the name of your custom post type then re-save your Permalink settings.

Otherwise, it may be a problem with the code in your taxonomy-cpt-type.php file.

i believe tag is a reserved taxonomy rewrite name on wordpress to be used on default post_tag taxonomy. That might cause the issue. Rename the custom taxonomy to something like coupon-tag.

BTW: did you try flushing the rewrites by visiting permalink page from settings tab?

First off, let's make sure you understand the template hierarchy. For a post type named coupon with 'has_archive' => true and a taxonomy named coupon-tag (following @Sisir's advice), both set to public,

• /coupon/ will use archive-coupon.php, archive.php, or index.php, whichever is found in that order
• /coupon-tag/foo/ will use taxonomy-coupon-tag-foo.php, taxonomy-coupon-tag.php, taxonomy.php, archive.php, or index.php, whichever is found first in that order. Note that archive-coupon.php is not in this list (that's a common mistake).
• home.php will only be used for the homepage

Next, tag is a special word and you will encounter rewrite conflicts using that as your slug. You should use something else.

Lastly, flushing your rewrites is very important here, and you need to remember to do it after any changes to any of the relevant code (any changes to the CPT or taxonomy). The easiest way to do so is to go to Settings → Permalinks and click "Save Changes".