Data migration from to 2.3.4 : Fatal error How to solve this issue?

After migration from to 2.3.4 : Fatal error: Uncaught TypeError: Argument 3 passed to Magento\Framework\View\Element\UiComponentFactory::mergeMetadataElement() must be of the type array, null given. How to solve this issue?

Code path : lib/internal/Magento/Framework/View/Element/ UiComponentFactory .php Function : mergeMetadataElement

protected function mergeMetadataElement(array $bundleComponents, $name, array $data, $reverseMerge = false)
    if (isset($bundleComponents[$name])) {
        $bundleComponents[$name] = $reverseMerge
            ? array_replace_recursive($data, $bundleComponents[$name])
            : array_replace_recursive($bundleComponents[$name], $data);
        return [$bundleComponents, true];
    } else {
        foreach ($bundleComponents as &$childData) {
            if (isset($childData['attributes']['class'])
                && is_a($childData['attributes']['class'], \Magento\Ui\Component\Container::class, true)
                && isset($childData['children']) && is_array($childData['children'])
            ) {
                list($childData['children'], $isMerged) = $this->mergeMetadataElement(
                if ($isMerged) {
                    return [$bundleComponents, true];
    return [$bundleComponents, false];

Well, I think we would have to see a lot of your code to fix this. But, I did a little research and found that a lot of people have had this problem. Actually a lot of people! You can see how others have fixed in here:
error-uicomponentfactory I think one of these might solve it for you.

Good luck!

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