I’ve read previous threads that cover this issue for navbars and menus but it does not seem to apply. I have a very simple example: two cards, one opened by default the other collapsed. When I try to expand the second card by pressing Card 2 Button, it opens but then immediately closes again. I am not sure what I’m doing wrong.
Example here:
<div id="accordion">
<div class="card">
<div class="card-header" id="header1">
<h5 class="mb-0">
<button class="btn btn-link" data-toggle="collapse" data-target="#collapse1" aria-expanded="true" aria-controls="collapse1">
Card 1 Button
</button>
</h5>
</div>
<div id="collapse1" class="collapse show" aria-labelledby="header1" data-parent="#accordion">
<div class="card-body">
Card 1 Content
</div>
</div>
</div>
<div class="card">
<div class="card-header" id="header2">
<h5 class="mb-0">
<button class="btn btn-link collapsed" data-toggle="collapse" data-target="#collapse2" aria-expanded="false" aria-controls="collapse2">
Card 2 Button
</button>
</h5>
</div>
<div id="collapse2" class="collapse" aria-labelledby="header2" data-parent="#accordion">
<div class="card-body">
Card 2 Content
</div>
</div>
</div>
</div>
Answer
Are you sure you are using Bootstrap 4?
In bootstrap 3 it works like following,
You need to use in class instead of show to make it open by default at the page load.
<div id="collapse1" class="collapse in" aria-labelledby="header1" data-parent="#accordion">
<div class="card-body">
Card 1 Content
</div>
</div>
jsFiddle https://jsfiddle.net/0uk0xuvd/
Check your bootstrap version that your are importing.