How to send select input data for form submission?

Question

I am loading Select input data from viewbag. but when click on seach button it is throwing an error at Viewbag.Events. How can pass eventcode from form submission to index post method? any other alternatives

<div class="col-md-6">
<form asp-action="Index">
    <div class="row mb-3">
        <div class="col-sm-6">
                       
            <div class="input-group">
                <select class ="form-control" id="eventCode" name="eventCode"  data_placeholder="Enter event code for search" class="chosen-select">
                    @foreach (var item in ViewBag.Events)
                    {
                        <option value="@item">@item</option>
                    }
                </select>
            </div>
        </div>
        <div class="col-sm-2"><button type="submit" class="btn btn-primary">Search</button></div>
    </div>
</form>