Jira Custom Field problems

I try to add a new custom field to Jira Issues. And I’ve faced few problems.

  1. JS code of Select2 becomes available and works only by inserting script below in a velocity edit file. $webResourceManager.requireResource("com.atlassian.auiplugin:aui-select2") and other similar methods doesn’t work. Why? How I can fix it?
<script type="text/javascript">
        AJS.toInit(function () {
  1. If I use script above, custom field with Select2 will mostly work correct. But in Issue Screen when I try to add my field by menu “Admin->Add field”, bottom “Submit” will change design and won’t be work. Field will not added. What’s the problem?

My edit velocity file code:

#controlHeader ($action $customField.id $customField.name $fieldLayoutItem.required $displayParameters.noHeader)
<form class="aui" style="width: available">
    <script type="text/javascript">
        AJS.toInit(function () {

    <select class="js-example-placeholder-single js-states form-control" name="$customField.id" id="$customField.id" style="width: inherit">
        #foreach ($option in $options)
            <option value="$option">$option</option>
#controlFooter ($action $fieldLayoutItem.fieldDescription $displayParameters.noHeader)

My atlassian-plugin.xml web-resource dependencies:

<web-resource key="aui-fields-resources" name="aui-fields Web Resources"> 
    <resource type="download" name="aui-fields.css" location="/css/aui-fields.css"/>  
    <resource type="download" name="aui-fields-js.js" location="/js/aui-fields-js.js"/>
    <resource type="download" name="images/" location="/images"/>  

Jira v.8.19.1, Atlassian SDK v.8.2.7

I solved both issues.
If somebody have a same problem, you’ll read a text below.

  1. Use this tutorial. Since JIRA 5.0 WebResourceManager is no longer supported.

  2. I removed <form></form> wrapper and the button started working.