Adding custom Image attribute for category in magento 2

Question

I have tried below code for adding thumbnail image in category.

When i upload image in custom field i get below error.

Error

Attention

The file was not uploaded.

error: "The file was not uploaded." errorcode: 666

category_form.xml

<field name="thumbnail_image">
 <argument name="data" xsi:type="array">
 <item name="config" xsi:type="array">
 <item name="dataType" xsi:type="string">string</item>
 <item name="source" xsi:type="string">category</item>
 <item name="label" xsi:type="string" translate="true">Category Image</item>
 <item name="visible" xsi:type="boolean">true</item>
 <item name="formElement" xsi:type="string">fileUploader</item>
 <item name="elementTmpl" xsi:type="string">ui/form/element/uploader/uploader</item>
 <item name="previewTmpl" xsi:type="string">Magento_Catalog/image-preview</item>
 <item name="required" xsi:type="boolean">false</item>
 <item name="sortOrder" xsi:type="number">40</item>
 <item name="uploaderConfig" xsi:type="array">
 <item name="url" xsi:type="url" path="catalog/category_image/upload"/>
 </item>
 <item name="label" xsi:type="string" translate="true">Thumbnail Image</item>
 </item>
 </argument>
 </field>

InstallData.php

$eavSetup->addAttribute('catalog_category', 'thumbnail_image', array(
 'input' => 'image',
 'type' => 'varchar',
 'backend' => 'catalog/category_attribute_backend_image',
 'group' => 'General',
 'label' => 'Thumbnail Image',
 'visible' => 1,
 'required' => 0,
 'user_defined' => 1,
 'frontend_input' =>'',
 'global' => \Magento\Catalog\Model\ResourceModel\Eav\Attribute::SCOPE_GLOBAL,
 'visible_on_front' => 1,
));

di.xml

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../lib/internal/Magento/Framework/Acl/etc/di.xsd">
<type name="Namespace\Module\Controller\Adminhtml\Category\Image">
 <arguments>
 <argument name="imageUploader" xsi:type="object">Magento\Catalog\CategoryImageUpload</argument>
 </arguments>
</type>
</config>

• Pratik: check this link magento.stackexchange.com/questions/129870/…
• Deeban Babu: Please check updated question still i have same issue
• Pratik: check this module on github github.com/pratikmage/magento2-subcategory
• Deeban Babu: @Pratik I checked that module now error not showing file upload successfully but image not stored in db
• Pratik: it's bug in magento and it's fix by following patch github.com/magento/magento2/pull/5978/files