Error uploading images/documents via Paperclip. What could be the problem?

Question

Ruby on Rails

Good afternoon, I'm facing an error that when uploading images to S3 via Paperclip I get an error has an extension that does not match its contents . I don’t experience such problems on a local machine, only on production. I started seeing this after updating rails 4.1.1 -> 4.1.16 and ruby ​​2.1.5 -> 2.3.1 and changing the instance to AWS .
Here is my validation:

validates_attachment    :document,
                        content_type: { not: "application/x-msdownload" }

I don't understand what is the problem. Any file I upload, whether it's an image or a document (of any extension), I get this error. Tell me please, what could be the reason for this?