Bootstrap modal closes on dropdownlist selected index change

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I used update Panel, but still the page is refreshing. Kindly help.

Recipe:

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CssClass="table table-striped table-hover" Font-Size="11pt" AlternatingRowStyle-BackColor="#FAAC58"

HeaderStyle-BackColor="orange" Width="100%" AllowPaging="true" ShowFooter="true"

RowStyle-BorderColor="White" BorderColor="White" OnPageIndexChanging="OnPaging"

OnRowEditing="EditRecipe" DataKeyNames="ERS_RECIPE_SKIP_ID" OnRowUpdating="UpdateRecipe"

OnRowCancelingEdit="CancelEdit" PageSize="12">

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Recipe

OnClick="btnClearAll_Click" />

OnClientClick="return confirm('Do you want to delete?')" Text="Delete" OnClick="DeleteRecipeFn">

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