When uploading a particular file it fails with a 406, Not Acceptable error message.
Effective April 9, 2016, all inbound file uploads are scanned for viruses before being saved on the server. If a file is found to contain a virus, it is rejected with a 406, Not Acceptable message. File scanning is performed to reduce the threat of hackers.
False positives may exist; however, you are strongly urged to verify the integrity of the file by running it through an anti-virus on your machine or through VirusTotal‘s free, online service. If the file comes back negative, open a ticket in the control panel with the attached specimen for further evaluation.