DB. Browser.Sqlite.OperationalError: database is locked

I am trying to submit a form into DB Browser Sqlite. I've created a table. I am able to store the data into Sqlite. However, once I add in a function to execute a cofirmation popup box in submit button (submitclaim.html), I was displayed with this error

sqlite3.OperationalError: database is locked

When I try to submit a form to the table, it occurs on the line:

    c.execute("INSERT INTO SubmitClaim VALUES (?,?,?,?,?)", (depart, type, uploadre, amt, description)

This is my app.py

@app.route('/addrec', methods=['POST', 'GET'])
def addrec():
    if request.method == 'POST':

        depart = request.form['depart']
        type = request.form['type']
        uploadre = request.form['uploadre']

        amt = request.form['amt']
        description = request.form['description']

    conn = sql.connect(db_path)
    c = conn.cursor()

    c.execute(
        "INSERT INTO SubmitClaim VALUES (?,?,?,?,?)", (depart, type, uploadre, amt, description))

    conn.commit()

    c.execute("SELECT * FROM  SubmitClaim")
    print(c.fetchall())
    conn.close()

    return render_template('base.html', user=session["user"], version=msal.__version__)
     

This is my SubmitClaim.html

<div class="arrange3">
    <button onclick="myFunction()" type="submit" class="submit-button" name="save", value="save">Submit</button>
    <script>
    function myFunction() {
    confirm("Press a button!");
    }

You just have to close the Database in DB Browser SQLITE and run the code