I still have issue. it looks like FilterDataProvider init was never called. I attached the log for extension and firewall app. extension.log firewall1.log firewall2.log

I saw below also /Applications/SimpleFirewall.app/Contents/Library/SystemExtensions/com.example.apple-samplecode.SimpleFirewallML4HRHFY98.SimpleFirewallExtension.systemextension: entitlement com.apple.developer.endpoint-security.client not present or not true debug 09:11:21.169301-0800 SimpleFirewall failed to fetch /Applications/SimpleFirewall.app/Contents/Library/SystemExtensions/com.example.apple-samplecode.SimpleFirewallML4HRHFY98.SimpleFirewallExtension.systemextension/Contents/_CodeSignature/CodeRequirements-1 error=-10 debug 09:11:21.169342-0800 SimpleFirewall SecStaticCode network default: YES debug 09:11:21.169404-0800 SimpleFirewall close(16) err: 0 default 09:11:21.169770-0800 SimpleFirewall Saving configuration SimpleFirewall with existing signature (null) when I debug the code, both below are called NEProvider.startSystemExtensionMode() IPCConnection.shared.startListener() Starting XPC listener was called. The App registered was called. Strange thing is that FilterDataProvider init was not called.

tried above, it is not working. My co-worker experience the same problem.