i am new in indexedddb.

when I want to create a transaction with a inceased version of the database (I increase the version because otherwise the upgradneeded event is never executed), I have the error "A version change transaction is running" which displays.

that's my code (it's from MDN):

var request = window.indexedDB.open("new-db", 8);

request.addEventListener('upgradeneeded', event => {
    console.log("bonjour");

    var db = event.target.result;

    var request = db.transaction([], "readwrite")
        .objectStore("customers")
        .delete("444-44-4444");
    request.onsuccess = function (event) {
        // c'est supprimé !
    };

});

request.onsuccess = function () {
    console.log("open");

}

THANKS FOR YOUR HELP.