Hello,
Please make sure that your vendor has the right permission to upload the file. You have to set the permission for the upload directory to “655” or “777”. If you have set correctly and still getting the error then please let us know.
If not and the issue exists please check the plugin conflict. Deactivate all plugin except for WooCommerce and Dokan. Then try again and take note.
If the issue exists to keep a strong backup of your site and allow me permission to check through your site and contact here.
Thanks ??
Looking forward to hearing from you,