Should I upgrade to macOS Sequoia? (Part 2)

ChristianChristian on Little Snitch, Security, Mac —

This is a follow-up to our previous recommendation advising against upgrading to macOS Sequoia 15.0. Just over two weeks after the public launch of Sequoia, Apple has released its first bugfix update (15.0.1) on October 3rd. So, should you upgrade now?

What was fixed?

There were two major concerns with the 15.0 version which affected Little Snitch as well as other third-party firewalls:

  1. ssh connections failing or aborting due to corrupted data in the TCP stream.
  2. Apple’s built-in firewall preventing DNS lookups of computer names.

The good news: According to our tests, the issue with the built-in firewall appears to be fixed.

However, the ssh issue was never consistently reproducible. For some users, it happened every time, for others, only sporadically. Most users were not affected at all. Since no one on our team experienced the issue firsthand, we lack direct experience with it. Recent user feedback indicates a shift of the situation: users who consistently encountered the problem no longer report it, while others, who were previously unaffected, are now experiencing ssh connections dropping after some time. We don't yet have sufficient data to determine whether this is coincidence or if the bug persists.

Are there new bugs?

We have received several reports from users of Little Snitch and Little Snitch Mini where the network content filter became inactive in the course of installing the macOS update. You’ll notice that you are affected if the Network Monitor stops displaying traffic or if connection blocking no longer works.

Fortunately, there appears to be a simple workaround. Open System Settings > Network > VPN & Filters and check the Filters & Proxies section. Little Snitch should be enabled and marked with a green dot. However, if the content filter is inactive, it will display a yellow or red dot:

In that case, select the inactive content filter and click the Minus-button at the bottom to remove it. Then open Little Snitch or Little Snitch Mini and re-enable the network filter. It should then be up and running again.

Conclusion

In summary: If you have already upgraded to Sequoia, we recommend installing the 15.0.1 bugfix release. If you’re still on Sonoma, it’s a trade-off between accessing new features and maintaining system stability. We don’t have a definitive recommendation — it depends on your personal preferences.

In any event, check the Filters & Proxies section in System Settings after the upgrade to ensure that your network content filters are still active.