I'm getting following issue when I'm click associated products.
main.INFO: Cache file with merged layout: LAYOUT_adminhtml_STORE1_321f776dd692abd332ec2bb61e502b692 and handles default, attachments_attachments_attachment_products: Please correct the XML data and try again. complex type 'handleType', attribute 'base': The QName value 'layoutType' does not resolve to a(n) simple type definition. Line: 47 [] [] [2016-07-15 13:35:01] main.INFO: Cache file with merged layout: LAYOUT_adminhtml_STORE1_3cf9ab1b1723bedc1dcd665a812b00335 and handles admin-1column: Please correct the XML data and try again. complex type 'handleType', attribute 'base': The QName value 'layoutType' does not resolve to a(n) simple type definition. Line: 47 [] [] 
<?xml version="1.0"?> <page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd"> <body> <block class="Magento\Framework\View\Element\Text\ListText" name="root"> <block class="Web4pro\Attachments\Block\Adminhtml\Attachment\Edit\Tab\Product" name="attachment.edit.tab.product"/> <block class="Magento\Backend\Block\Widget\Grid\Serializer" name="product_grid_serializer"> <reference name="product_grid_serializer"> <action method="initSerializerBlock"> <arguments> <argument xsi:type="string" name="grid_block_name">attachment.edit.tab.product</argument> <argument xsi:type="string" name="data_callback">getSelectedProducts</argument> <argument xsi:type="string" name="hidden_input_name">products</argument> <argument xsi:type="string" name="reload_param_name">attachment_products</argument> </arguments> </action> <action method="addColumnInputName"> <arguments> <argument xsi:type="string" name="input_name">position</argument> </arguments> </action> </reference> </block> </block> </body> </page> Please find code below url. https://github.com/sivajik34/Magento2-Product-Attachments
