I am now thinking that the issue is not with socketfilterfw, but with the encoding of the path. I noticed on Catalina that Xcode will add your app to the firewall, if you open a socket and are listening to it. So I moved my simple socket server over to Beta 11.1 and ran it. At first, nothing happened, but after setting the global state on, the app appeared. As you will see, there is now a valid path being displayed in socketfilterfw, but when I try to remove it, I get the same error "The file path you specified is invalid". Here is my terminal session: vagrant@Vagrants-Mac ~ % sudo /usr/libexec/ApplicationFirewall/socketfilterfw --listapps vagrant@Vagrants-Mac ~ % sudo /usr/libexec/ApplicationFirewall/socketfilterfw --setglobalstate on Firewall is enabled. (State = 1) vagrant@Vagrants-Mac ~ % sudo /usr/libexec/ApplicationFirewall/socketfilterfw --listapps ALF: total number of apps = 1 1 : /Users/vagrant/Library/Developer/Xcode/DerivedData/SocketServer-ftagnsjglzldkpdpxewhonpchqay/Build/Products/Debug/SocketServer.app ( Allow incoming connections ) vagrant@Vagrants-Mac ~ % sudo /usr/libexec/ApplicationFirewall/socketfilterfw --remove /Users/vagrant/Library/Developer/Xcode/DerivedData/SocketServer-ftagnsjglzldkpdpxewhonpchqay/Build/Products/Debug/SocketServer.app The file path you specified is invalid vagrant@Vagrants-Mac ~ % locale LANG="enUS.UTF-8" LCCOLLATE="enUS.UTF-8" LCCTYPE="enUS.UTF-8" LCMESSAGES="enUS.UTF-8" LCMONETARY="enUS.UTF-8" LCNUMERIC="enUS.UTF-8" LCTIME="enUS.UTF-8" LCALL= vagrant@Vagrants-Mac ~ % sw_vers ProductName: macOS ProductVersion: 11.1 BuildVersion: 20C5048k vagrant@Vagrants-Mac ~ %

Update - The error message "The file path you specified is invalid" continues with Big Sur 11.01 release and 11.1 Beta (20C5048k).

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Matt, thank you for your reply. I am definitely using an absolute path and as soon as Big Sur has been officially released, I can do one more test and file a bug report, if it is still happening.