Adding Thumbnail to CPT Issue

Hello,

I added a custom post type with support for thumbnails. The theme also has support for post-thumbnails, but I am having an issue attempting to upload featured images to this custom post. I have no issues adding featured images to regular posts, but when I try to upload an image to the custom post type I get an error, stating that ‘An Error Occured in the upload, please try again later.

Please help!