Форуми / Cotonti / Support / Extrafield Textarea for some reason modifies the uploaded content

Hi staleo,

It's most likely HTML Purifier filtering the data-caption attributes.

Try adding this to /plugins/htmlpurifier/presets/htmlpurifier.group_5.preset

$def = $config->getHTMLDefinition(true);
$def->addAttribute('img', 'data-caption', 'Text');