Getting Fatal Error on psoting/updating Posts via Rest API

Hello Peter,

thank you for clarification.
But this was working before. Why can't I update my products any more?
I need MetaBox mostly to add custom fields to products which will be updated by json I get from another database.
Is there a workaround?

I started this project in October last year and I could post/update the woo commerce simple product without any problem. In summer, I got an error 500 but the fields were still filled with the correct data.
Now, I get the error and the fields don’t contain any value.
Here is a sample json I send to the Rest API:

<div> POST https://hannl.bw-works.com/wp-json/wc/v3/products/1477
"meta_box": {
		"relatedbook": [],
		"relatedlist": "",
		"herobooks": [],
		"lesetipp": [],
		"rel_products": [],
		"untertitel": "Metatesti",
		"format": "24 x 17",
		"einband": "Softcover",
		"illus": "mit zahlreichen Fotos",
		"umfang": "384",
		"autor": "Mark Andrews",
		"autor_2": "Michael Bergmeister",
		"autor_3": "Andreas Leibetseder",
		"translator": "Kirsten Borchardt",
		"translator_2": "",
		"translator_3": "",
		"isbn": "9783854457350",
		"preis_at": "27",
		"preis_ch": "",
		"pubdate": "20221121",
		"zitat": "Unterhält jeden, in dessen Vergangenheit eine Flasche schwarzer Farbe herumlungert",
		"zitatquelle": "Victoria Segal, Mojo",
		"zitat_2": "Das Buch gibt einen genauen Einblick, warum Eldritch zu einem der schwierigsten Menschen wurde, mit denen man in der Branche arbeiten kann …",
		"zitatquelle_2": "on-magazine.co.uk",
		"zitat_3": "",
		"zitatquelle_3": "",
		"ebook": "1",
		"ebook_isbn": "9783854450000",
		"ebookpreis": "12",
		"version": "",
		"uebersetzter-und-buecher_from": [],
		"autor-und-buecher_to": [],
		"3dcover": {
			"width": 150,
			"height": 150,
			"file": "2022\/10\/som3d.jpg",
			"filesize": 34023,
			"sizes": {
				"medium": {
					"file": "som3d-238x300.jpg",
					"width": 238,
					"height": 300,
					"mime-type": "image\/jpeg",
					"filesize": 18220,
					"url": "https:\/\/hannl.bw-works.com\/wp-content\/uploads\/2022\/10\/som3d-238x300.jpg"
				}
</div>

This is the response in Insomnia:

<div><styletype="text/css">.wp-die-message{
	display: none;
}</style><linkrel="stylesheet"href="https://hannl.bw-works.com/wp-content/plugins/query-monitor/assets/query-monitor.css?ver=3.15.0"media="all"/><divdata-qm="qm"><divid="qm-fatal"data-qm-message="Uncaught Error: MetaBox\RestApi\Post::update(): Argument #2 ($post) must be of type WP_Post, WC_Product_Simple given, called in /home/hannl/public_html/wp-includes/rest-api/endpoints/class-wp-rest-controller.php on line 474"data-qm-file="wp-content/plugins/mb-rest-api/src/Post.php"data-qm-line="7"><divclass="qm-fatal-wrap"><p><b>Fatalerror</b>: UncaughtError: MetaBox\RestApi\Post: : update(): Argument#2($post)mustbeoftypeWP_Post,
WC_Product_Simplegiven,
calledin/home/hannl/public_html/wp-includes/rest-api/endpoints/class-wp-rest-controller.phponline474<br>in<b>/home/hannl/public_html/wp-content/plugins/mb-rest-api/src/Post.php</b>online<b>7</b></p><p>Callstack: </p><ol><li><code>MetaBox\RestApi\Post: : update()</code><br><spanclass="qm-info qm-supplemental">wp-includes/rest-api/endpoints/class-wp-rest-controller.php: 474</span></li><li><code>WP_REST_Controller: : update_additional_fields_for_object()</code><br><spanclass="qm-info qm-supplemental">wp-content/plugins/woocommerce/includes/rest-api/Controllers/Version3/class-wc-rest-crud-controller.php: 245</span></li><li><code>WC_REST_CRUD_Controller: : update_item()</code><br><spanclass="qm-info qm-supplemental">wp-includes/rest-api/class-wp-rest-server.php: 1193</span></li><li><code>WP_REST_Server: : respond_to_request()</code><br><spanclass="qm-info qm-supplemental">wp-includes/rest-api/class-wp-rest-server.php: 1041</span></li><li><code>WP_REST_Server: : dispatch()</code><br><spanclass="qm-info qm-supplemental">wp-includes/rest-api/class-wp-rest-server.php: 431</span></li><li><code>WP_REST_Server: : serve_request()</code><br><spanclass="qm-info qm-supplemental">wp-includes/rest-api.php: 424</span></li><li><code>rest_api_loaded()</code><br><spanclass="qm-info qm-supplemental">wp-includes/class-wp-hook.php: 324</span></li><li><code>WP_Hook: : apply_filters()</code><br><spanclass="qm-info qm-supplemental">wp-includes/class-wp-hook.php: 348</span></li><li><code>WP_Hook: : do_action()</code><br><spanclass="qm-info qm-supplemental">wp-includes/plugin.php: 565</span></li><li><code>do_action_ref_array()</code><br><spanclass="qm-info qm-supplemental">wp-includes/class-wp.php: 418</span></li><li><code>WP: : parse_request()</code><br><spanclass="qm-info qm-supplemental">wp-includes/class-wp.php: 813</span></li><li><code>WP: : main()</code><br><spanclass="qm-info qm-supplemental">wp-includes/functions.php: 1336</span></li><li><code>wp()</code><br><spanclass="qm-info qm-supplemental">wp-blog-header.php: 16</span></li><li><code>require()</code><br><spanclass="qm-info qm-supplemental">index.php: 17</span></li></ol></div><h2>QueryMonitor</h2></div></div>{
	"code": "internal_server_error",
	"message": "<p>Es gab einen kritischen Fehler auf deiner Website.<\/p><p><a href="https:\/\/wordpress.org\/documentation\/article\/faq-troubleshooting\/">Erfahre mehr über die Problembehandlung in WordPress.<\/a><\/p>",
	"data": {
		"status": 500
	},
	"additional_errors": []
}
</div>

Thank you, that was the problem.