Summary
We are activating a Network Extension system extension (filter-data) from a signed and notarized macOS app.
Activation consistently fails with:
OSSystemExtensionErrorDomain code=4
Extension not found in App bundle. Unable to find any matched extension with identifier: com.seaskylight.yksmacos.ExamNetFilter.data
At the same time, sysextd logs:
no policy, cannot allow apps outside /Applications
However, our host app and executable real paths are already under /Applications, and the extension bundle physically exists in the expected app bundle location.
Environment
macOS: Darwin 25.4.0
Host app: /Applications/xxx.app
Host bundle id: com.seaskylight.yksmacos
System extension bundle id: com.seaskylight.yksmacos.ExamNetFilter.data
Team ID: BVU65MZFLK
Device management:
Enrolled via DEP: No
MDM enrollment: No
Reproduction Steps
Install host app to /Applications.
Launch host app via Finder or:
open -a "/Applications/xxx.app"
Trigger OSSystemExtensionRequest activationRequestForExtension for:
com.seaskylight.yksmacos.ExamNetFilter.data
Observe failure callback (code=4).
Collect logs:
log show --last 2m --style compact --info --debug --predicate 'process == "sysextd"'
systemextensionsctl list (shows 0 extension(s))
Observed Results
sysextd
client activation request for com.seaskylight.yksmacos.ExamNetFilter.data
attempting to realize extension with identifier com.seaskylight.yksmacos.ExamNetFilter.data
no policy, cannot allow apps outside /Applications
App-side diagnostics (captured at failure)
pid=3249
bundlePath=/Applications/xxx.app
bundlePathReal=/Applications/xxx.app
execPath=/Applications/xxx.app/Contents/MacOS/xxx
execPathReal=/Applications/xxx.app/Contents/MacOS/xxx
extPath=/Applications/xxx.app/Contents/Library/SystemExtensions/ExamNetFilterData.systemextension
extExists=true
runningFromHelper=false
Error callback
NSError{domain=OSSystemExtensionErrorDomain code=4 desc=Extension not found in App bundle...}
Additional Validation
We reproduced the same failure using a minimal native host app (SysExtProbe) in /Applications that only submits the activation request for the same extension identifier.
It also fails with OSSystemExtensionErrorDomain code=4, indicating this is not specific to Electron app logic.
Signing / Packaging Notes
Host app and system extension are signed with the same Team ID (BVU65MZFLK).
System extension bundle exists under:
/Applications/xxx.app/Contents/Library/SystemExtensions/ExamNetFilterData.systemextension
Extension Info.plist contains bundle id:
com.seaskylight.yksmacos.ExamNetFilter.data
Host app includes NSSystemExtensionUsageDescription.
Questions for DTS
In non-MDM personal-device scenarios, what exact conditions trigger sysextd to emit:
no policy, cannot allow apps outside /Applications even when both bundlePath and realpath are in /Applications?
Can code=4 (“Extension not found in App bundle”) be returned for policy/state reasons even when extension bundle is present and identifier matches?
Are there known sysextd policy/cache states that cause this behavior, and what is the recommended recovery procedure?
Topic:
App & System Services
SubTopic:
Networking
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