Error Message Says FileZilla Will Damage My Computer After updating to Catalina, when I start FileZilla, I get the error message &quot;filezilla will damage your computer. you should move it to the bin”. I had installed FileZilla from the App Store, and not directoy from the Filezilla Website.
I found a few discussions on this topic - also mentioning FileZilla explicitly - on the net, usually in combination with an advertisement for some &quot;mal cleaner software&quot; (for example here). Before the upgrade, I had used FileZilla frequently, and did not notice any problem.
Is this a false alarm by the Gatekeeper, or should I suspect that this app indeed is infected and remove it?
I recommend binning the app in this case. Get a new copy or different tool.
The FileZilla downloads and updates now contain PUP - potentially unwanted program (or PUS if software makes more sense than program). The line between malware, adware and privacy stealing information is blurred and when a package has these modifications you will sometimes be prompted with a warning. Even when the owner of a tool decides to monetize their tool, Apple is generally flagging that change with a signing error so people know a common tool isn’t what it was in the past.
This warning can be as simple as the application is modified and what was signed isn’t what is running anymore.
Many people have repackaged this app, so be sure you do the work to get a clean copy or perhaps delete it and redownload. I love Mountain Duck and cyberduck for this if you find the zilla hassle too great to get it reinstalled.

https://medium.com/web-design-web-developer-magazine/how-to-safely-download-and-cleanly-install-filezilla-ftp-software-with-no-additional-junk-10b27a2d270d
https://cyberduck.io/
https://mountainduck.io/