Cant post to api. 400 fetch error (React)

Question

I have an issue when i am trying to post to my API (Net6.0) because i get the error of 400 fetch, i have tried different things that i have found on here but i cant seem to fix it.

Here is my code:

my function:

const [title, setTitle] = useState('');
const [description, setDescription] = useState('');
const [link, setLink] = useState('');

const handleSubmit =(e) => {
    e.preventDefault();
    const post = { title, description, link };
    fetch('https://localhost:7018/api/Posts', {
        method: 'POST',
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify(post)
    }).then(() => {
        console.log('new post added');
        // GoBack()
    })
}

and my return:

<div className="create">
    
    <form onSubmit={handleSubmit}>
        <label>Titel</label>
        <input 
            type="text"
            required
            value={title}
            onChange={(e) => setTitle(e.target.value)}
        />
        <label>Description</label>
        <textarea
            required
            value={description}
            onChange={(e) => setDescription(e.target.value)}
        ></textarea>
        <label>Link</label>
        <input 
            type="text"
            required
            value={link}
            onChange={(e) => setLink(e.target.value)}
        />
        <button>Skapa Inlägg</button>
        <p>{ title }</p>
        <p>{ description }</p>
        <p>{ link }</p>
    </form>
</div>

here is the error code i get [1]: https://i.stack.imgur.com/WHwTn.png