Error message: File Extension Not Supported Exception

Hi Forum,

maybe you can help me.

I am following this tutorial LINK to add a new file extenstion to my new shopware shop. Instead of img I would like to allow stl as well. But I am getting this error message in debug.log.

[2022-11-10T21:20:34.710024+00:00] request.INFO: Matched route „api.action.media.upload“. {„route“:„api.action.media.upload“,„route_parameters“:{„_route“:„api.action.media.upload“,„_routeScope“:[„api“],„_controller“:„Shopware\Core\Content\Media\Api\MediaUploadController::upload“,„mediaId“:„0003491cfbb54836a11a0a7876ec06da“},„request_uri“:„https://www.domain.com/api/_action/media/0003491cfbb54836a11a0a7876ec06da/upload?extension=stl&fileName=Batterien-AAA",„method“:"POST“}

[2022-11-10T21:20:34.757928+00:00] request.ERROR: Uncaught PHP Exception Shopware\Core\Content\Media\Exception\FileExtensionNotSupportedException: „The file extension „stl“ for media object with id 0003491cfbb54836a11a0a7876ec06da is not supported.“ at /var/www/clients/clientx/web123/web/vendor/shopware/core/Content/Media/File/FileSaver.php line 399 {„exception“:„[object] (Shopware\Core\Content\Media\Exception\FileExtensionNotSupportedException(code: 0): The file extension "stl" for media object with id 0003491cfbb54836a11a0a7876ec06da is not supported. at /var/www/clients/clientx/web123/web/vendor/shopware/core/Content/Media/File/FileSaver.php:399)“}

Does someone can give me a hint?

BR