i used CollectionType with FileType. Everything is working good but problem is with render this after validation error.
I tried to write code with help of this article: http://growingcookies.com/easy-multiple-file-upload-in-symfony-using-the-collectiontype-field/
Symfony documentation dont have anything about render after validation error.
{% set pos = 0 %}
{% for doc in form.images %}
<div class="image-button-block">
<button type="button" class="btn btn-danger btn-sm remove-image-button" onclick="removeFile($(this));"><i class="fa fa-times" aria-hidden="true"></i></button>
<div style="display: none">
{{ form_row(doc) }}
</div>
</div>
{% set pos = pos + 1 %}
{% endfor %}
After that when i send this form one more time with fixed validation error. I got null in images array.