Taxonomy `lang` not working in custom post with WP version 5.0 beta 2

[shahalom]

Just tried to work with WP version 5.0 beta 2 in one of my personal project. When I tried to edit a custom post I notice that one of my custom taxonomy (Name: lang, Title: Language) not working. Neither showing old terms nor able to create new!

When I clicked on "Add new term" in the Language taxonomy box, shows me "The editor has encountered an unexpected error." with three buttons. I have added the screenshot.

​http://www.mediafire.com/view/nx92yswjpq4yqpf/1.png

​http://www.mediafire.com/view/v94lcsaj503sn8n/2.png

When I click the "Copy Error" button and paste it on a text editor, it shows:

value@http://localhost/wp-projects/mcq-academy/wp-includes/js/dist/editor.min.js?ver=5.0-beta2:55:228224
Ed@http://localhost/wp-projects/mcq-academy/wp-includes/js/dist/vendor/react-dom.min.js?ver=5.0-beta2:92:134
Mf@http://localhost/wp-projects/mcq-academy/wp-includes/js/dist/vendor/react-dom.min.js?ver=5.0-beta2:91:440
ph@http://localhost/wp-projects/mcq-academy/wp-includes/js/dist/vendor/react-dom.min.js?ver=5.0-beta2:98:361
cg@http://localhost/wp-projects/mcq-academy/wp-includes/js/dist/vendor/react-dom.min.js?ver=5.0-beta2:123:489
dg@http://localhost/wp-projects/mcq-academy/wp-includes/js/dist/vendor/react-dom.min.js?ver=5.0-beta2:124:355
yc@http://localhost/wp-projects/mcq-academy/wp-includes/js/dist/vendor/react-dom.min.js?ver=5.0-beta2:136:144
R@http://localhost/wp-projects/mcq-academy/wp-includes/js/dist/vendor/react-dom.min.js?ver=5.0-beta2:135:187
lg@http://localhost/wp-projects/mcq-academy/wp-includes/js/dist/vendor/react-dom.min.js?ver=5.0-beta2:149:399
Ue@http://localhost/wp-projects/mcq-academy/wp-includes/js/dist/vendor/react-dom.min.js?ver=5.0-beta2:40:18

[pento]

@shahalom: We haven't had any other reports of this, are you still able to reproduce it?

[shahalom]

Replying to pento:

@shahalom: We haven't had any other reports of this, are you still able to reproduce it?

Again tried with the new released WP5.0 and no luck. I am still not seeing the lang taxonomies.

Let me describe how I update my dev site -

I have deleted all the files and folder of my dev site except the wp-content folder.

Updated the wp-config.php files with related information like- DB info, table prefix

Browse my dev site and it is ok in the frontend

Login to browse admin. On logged in successfully I got a screen to update my database. I clicked the button and it shows update complete.

Now I tried to edit or create a new custom post called mcq. My topic taxonomy shows all terms hierarchical.

In the lang taxonomy block showing only Add New Language button and when I clicked on it, it allows me to create a new language that does not already exist but not displaying existing terms.

[shahalom]

I have created a development/test version of the site. My request is to register at ​https://dev.mcqacademy.com/ and try to create a new post under MCQ post type ​https://dev.mcqacademy.com/wp-admin/post-new.php?post_type=mcq.

You will notice that language taxonomy has two terms in classic editor mode while these terms are not available in block mode.

[shahalom]

The error was producing from a custom plugin of the website. The plugin set a lower limit value for rest api response i; e, $endpoints['/wp/v2/lang'][0]['args']['per_page']['maximum'] = 10;. I have removed the line and everything is working.