i try this code but it not working with tab in form ui component:

<item name="additionalClasses" xsi:type="array">
    <item name="my-custom-class" xsi:type="boolean">true</item>
  • 1
    what you want to exactly? Commented May 24, 2019 at 10:15
  • i want add class to my custom tab in form ui component?
    – NewBie
    Commented May 24, 2019 at 10:17
  • Do you want to additionClass for form filed or left side custom tab? Commented May 24, 2019 at 10:57
  • left side custom tab
    – NewBie
    Commented May 24, 2019 at 10:58

2 Answers 2


Try this code to add additonalclasses for tab in form ui component.

More information in details, Visit, How to additonalClasses for Tab in Magento 2 UI component form

<fieldset name="address" sortOrder="30">
            <class name="custom-address">true</class>

Hope this helps. Thanks.


Try using following example:

<?xml version="1.0" encoding="UTF-8"?>
<form xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd">
    <fieldset name="websites" sortOrder="30">
        <argument name="data" xsi:type="array">
            <item name="config" xsi:type="array">
                <item name="additionalClasses" xsi:type="string">admin__field-medium</item>
  • It does not working with Magento 2.3 :(
    – NewBie
    Commented May 24, 2019 at 10:54
  • This is tested code in 2.3 :) Makesure you use this correctly
    – Sohel Rana
    Commented May 24, 2019 at 10:55
  • I tried it but nothing happened
    – NewBie
    Commented May 24, 2019 at 10:56
  • Your answer is right @SohelRana but it's for form filed... it want for custom left tab Commented May 24, 2019 at 10:59
  • yes, I apologize for not clarifying
    – NewBie
    Commented May 24, 2019 at 11:01

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