I am using Gravity Advanced Files uploader plugin for wordpress which use PLupload for file uploads.
I want it to allow .bmp and .dcm files to be uploaded. I was able to change the settings to allow those files types to be added with plupload by adding the file extension and also to the mime type list. But when I press start upload it comes back with those files as having a "file type error".
Resolved. The issue was actually the wordpress media library blocking those file types. I added this code to me funcitons.php file and problem solved.