TYPO3 Core

The popup closes immediately because of a failing TCA check.

This doesn't work in 7.6. The code in 8.4 seems to be the same. See also Bug #20420

TYPO3\CMS\Backend\Controller\Wizard\EditController::main() do some checks using TCA and some GET parameters. All checks are done using TCA configuration:

$config = $GLOBALS['TCA'][$table]['columns'][$field]['config'];

Unfortunately this will not work for flexforms because we need here the configuration of the flexform field, not the parent tt_content field (for example).

Attached is a patch. I see that as a proof of concept as it will not work with NEW records and the flexform handling is a bit un-generic. The comments in the code should that make clear.

Here's a flexform field for testing:

<settings.collections>
    <TCEforms>
        <label>LLL:EXT:cms/locallang_ttc.xlf:file_collections</label>
        <config type="array">
            <type>group</type>
            <internal_type>db</internal_type>
            <allowed>sys_file_collection</allowed>
            <maxitems type="integer">999</maxitems>
            <minitems type="integer">1</minitems>
            <size type="integer">5</size>
            <wizards type="array">
                <_VERTICAL type="integer">1</_VERTICAL>
                <edit type="array">
                    <type>popup</type>
                    <title>Edit</title>
                    <module type="array">
                        <name>wizard_edit</name>
                    </module>
                    <popup_onlyOpenIfSelected type="integer">1</popup_onlyOpenIfSelected>
                    <icon>actions-open</icon>
                    <JSopenParams>height=350,width=580,status=0,menubar=0,scrollbars=1</JSopenParams>
                </edit>
            </wizards>
        </config>
    </TCEforms>
</settings.collections>