Bulk upload notes - documents not a valid filetype

Hello everyone!

I want to bulk upload notes attachments to a specific contact.

i used this template :

Some of the columns are just to help me create the document name because i m uploading 1000 files.

So the upload works fine but when i try to open an attachment i get an error that the file type is not valid. I think this is something to do with the mime type although i'm not sure.

Anyone know what i'm doing wrong?

Thanks!