SonicWall’s gateway antivirus software gives the following message when trying to download something:
Gateway Anti-Virus Alert
This request is blocked by the Firewall Gateway Anti-Virus Service. Name: (Cloud Id: xxxxxxxx) trace (Trojan)
This is because either the thing you are trying to download contains a virus / threat, or because a “false positive” has been detected. A false positive is basically when an antivirus program incorrectly detects a file as being a virus.
To fix this, don’t download the file (ideally). Alternatively if you must downlaod the file and do not believe it to be contaminated with a virus, you can set an exception in the web interface of the SonicWall. If you do this, when you do download the file, I suggest running a virus scan from multiple antivirus vendors to confirm that it is definitely safe. I have found Virus Total to be particularly useful for this task.