fixes #11492 hopefully
For uploading files, the enctype for the form has to be set to `multipart/form-data`. Frio was missing this specification, other themes inherit it from the default template.
</form>
{{* Import contacts CSV *}}
- <form action="settings/account/importcontact" method="post" autocomplete="off" class="panel">
+ <form action="settings/account/importcontact" method="post" autocomplete="off" class="panel" enctype="multipart/form-data">
<input type="hidden" name="form_security_token" value="{{$form_security_token}}">
<div class="section-subtitle-wrapper panel-heading" role="tab" id="importcontact-settings">
<h2>