What could be the cause of the Bootstrap menu not working?

Question

The fact is that the bootstrap itself works and is actively used. Sending the code, would be times for any help!

<ul class="top-header-contact-info secondary-menu">
    <li class="nav-item dropdown-toggle">
        <a href="novosti">News</a>
        <ul class="dropdown-menu">
            <li class="nav-item">
                <a href="#" class="nav-link">The Secret of Your Business Success Find Quickly</a>
            </li>
        </ul>
    </li>
    <li class="nav-item dropdown-toggle">
        <a href="o-nas">About us</a>
        <ul class="dropdown-menu">
            <li class="nav-item">
                <a href="about-us" class="nav-link">About us</a>
            </li>
            <li class="nav-item">
                <a href="#" class="nav-link">About</a>
            </li>
        </ul>
    </li>
    <li class="nav-item dropdown-toggle">
        <a href="kontaktyi">Contacts</a>
    </li>
    <li class="nav-item dropdown-toggle">
        <a href="encziklopediya">Encyclopedia</a>
    </li>
</ul>

Answer 1

Try adding this: data-bs-toggle="dropdown"

<ul class="top-header-contact-info secondary-menu">
        <li class="nav-item dropdown-toggle" data-bs-toggle="dropdown">
            <a href="novosti">News</a>
            <ul class="dropdown-menu">
                <li class="nav-item">
                    <a href="#" class="nav-link">The Secret of Your Business Success Find Quickly</a>
                </li>
            </ul>
        </li>
        <li class="nav-item dropdown-toggle" data-bs-toggle="dropdown">
            <a href="o-nas">About us</a>
            <ul class="dropdown-menu">
                <li class="nav-item">
                    <a href="about-us" class="nav-link">About us</a>
                </li>
                <li class="nav-item">
                    <a href="#" class="nav-link">About</a>
                </li>
            </ul>
        </li>
        <li class="nav-item dropdown-toggle">
            <a href="kontaktyi">Contacts</a>
        </li>
        <li class="nav-item dropdown-toggle">
            <a href="encziklopediya">Encyclopedia</a>
        </li>
    </ul>