Big Sur Troubleshooting Guide

Version 2020.11.23

Big Sur update has introduced a number of major changes in macOS. One of them is disabling of Network Kernel Extensions (NKE) API that has been used by Proxifier for Mac v2. The new Network Extensions API has been introduced to replace it. We have rewritten the network part of Proxifier to adopt this change. Together with the other improvements it has been released as Proxifier for Mac v3.

Proxifier License Upgrade

Proxifier for Mac v3 requires a new license. Upgrade options depend on the date of v2 purchase.
If you purchase Proxifier for Mac v2 on or after:

You can extract your existing v2 key using one of the following commands in Terminal:
defaults read ~/Library/Preferences/com.initex.proxifier.macosx LicenseKey
sudo defaults read /Library/Preferences/com.initex.proxifier.macosx LicenseKey

Configuration Migration

Proxifier for Mac v3 has File->Import v2 Profile... menu command that allows you to import v2 profiles (configuration). Alternatively, you can save profile to a file using File->Export... in v2 and import this file using File->Import... in v3.

Proxifier for Mac v3 runs in a sandbox and it is technically impossible for it to migrate the profiles automatically.

Technical Issues

Unfortunately, the new Big Sur API is currently unstable. There are issues that persist when Proxifier is just running and they do not depend on Proxifier configuration or code. The bugs have been reported to Apple and hopefully will be resolved with the next Big Sur updates.

Please feel free to contact us at and we will do our best to help you.

Special Build to Address Big Sur Problems

To mitigate the problem, we have prepared an experimental build of Proxifier for Mac v2 that supports Big Sur using some private API.

You can try it or check v3 workarounds for some known issues listed below.

Applications Cannot Bind a Port for Listening

Applications report errors like "Protocol wrong type for socket", "Failed to find a free local port", "Protocol wrong type for socket (Listen failed)"


There is a bug in Network Extension API in the current version of macOS Big Sur. Apple has been aware of it since September. Hopefully, the problem will be fixed in the next Big Sur update.

Some Applications Cannot Access the Internet

Affected applications may include Safari, built-in ssh, Cisco Webex and others. You have a third-party VPN or firewall product like Cisco AnyConnect, Little Snitch, etc.


Most likely it is caused by a problem in Network Extension API. Apparently, two Network Extensions cannot run simultaneously in the current version of macOS Big Sur. We are working with Apple to resolve this.