Parallel Asset Uploads

When several assets are uploaded at once, Pimcore Studio sends at most five uploads at the same time and queues the rest. To change that limit, add this configuration:

pimcore_studio_ui:
    asset_upload:
        max_parallel_uploads: 5

Without a limit, the browser starts every selected file at once. Over HTTP/2 they all reach the server together, which can occupy every available PHP-FPM worker and make uploads fail with a 500 or 502. Lower the value if that happens, raise it if uploads feel slow and the server has capacity.