Can't update Connected account with token

Question

I tried to update a Connected Account using token like this :

$account = \Stripe\Account::retrieve($_POST['stripe_connect_edd_user']);
$account->account_token = $_POST['token_stripe_edd'];
$account->save();

But I've got this error :

Once a full set of basic legal entity information has been provided (type, business_name, first_name, last_name, and address), you cannot unset any of it, only update it.

The token is generated exactly like account creation, and Stripe Logs seems OK :

Any idea about what's wrong ?