Fetch : TypeError: NetworkError when attempting to fetch resource.

Hello,

I have this problem.

If I run this code step by step with the debuger, all works fine.

But if I run this code normally, I get this error.

TypeError: NetworkError when attempting to fetch resource.

I think that it can be a problem with synchon / asynchron function, but I already have a promise.

const apiUrl = 'http://localhost:5678/api/students';
fetch(apiUrl, {
    method: 'POST',
    headers: {
        'Authorization': `Bearer ${token}`
    },
    body: data,
}).then((res) => {
    if (res.ok) {
        console.log('success');
    } else {
        throw new Error('Error status code: ' + res.status);
    }
}).catch((error) => {
    console.log(error);
});

What could be the source of the problem ?

Thanks for your help.

V