TYPO3 Core

still valid - also for IconFactory in v7.

I couldn't validate this issue. Marc will report back if it happens again on his system or if there is any dependency to reproduce this.

This error can be reproduced when configuring a category field with a missing rootId

    'my_field' => [
        'config' => [
            'type' => 'select',
            'renderMode' => 'tree',
            'treeConfig' => [
                'parentField' => 'parent',
                'rootUid' => <NON EXISTING CATEGORY UID>,
                'appearance' => [
                    'showHeader' => TRUE,
                    'allowRecursiveMode' => TRUE,
                    'expandAll' => TRUE,
                    'maxLevels' => 99,
                    'width' => 700,
                ],
            ],
            'MM' => 'sys_category_record_mm',
            'MM_match_fields' => [
                'fieldname' => 'my_field',
                'tablenames' => 'tx_myext_my_table',
            ],
            'MM_opposite_field' => 'items',
            'foreign_table' => 'sys_category',
            'foreign_table_where' => ' AND (sys_category.sys_language_uid = 0 OR sys_category.l10n_parent = 0) ORDER BY sys_category.sorting',
            'size' => 10,
            'autoSizeMax' => 20,
            'minitems' => 0,
            'maxitems' => 99,
        ]
    ],