Hello Group,
we have a website running with an upload for media files. When i want to upload media then the following error is sent back to the browser:

upload:524 GET https://server.domain.name/swfuploader/upload.js.php?app=frontend&env=prod&debug=false&version=1613649786 net::ERR_ABORTED 400 (Bad Request)

Other php-based files are delivered correctly. Can u please help me to fix this?
Thank you!