JS: My API update PUT function is giving a 400 error when reaching Fetch()

[hollow totem]

function updateItem() {
    const itemId = document.getElementById('edit-id').value;
    const item = {
        id: parseInt(itemId, 10),
        name: document.getElementById('edit-name').value.trim(),
        description: document.getElementById('edit-desc').value.trim(),
        countryID: document.getElementById('edit-coid').value.trim()
    };

    fetch(`${uri}/${itemId}` + "?UserName=" + UserName, {
        method: 'PUT',
        headers: {
            'Accept': 'application/json',
            'Content-Type': 'application/json'
        },
        body: JSON.stringify(item)
    })
        .then(() => getItems())
        .catch(error => console.error('Unable to update item.', error));

    closeInput();

    return false;
}