Microsoft is unlocking the "Full Potential" of Private Channels in Microsoft Teams: What You Need to Know

It has been a while since I posted something just about a Microsoft Teams update, as a lot have been Copilot in Teams to be honest. But here is a real Microsoft Teams update I think is worth knowing about, and it involves Security and Compliance as well. Microsoft is rolling out a "major" update to private channels in Teams, starting in late September 2025 and continuing through mid-December. This biggest change in this update is a shift in how private channel data is stored from individual user mailboxes to a dedicated channel mailbox. Not only will this simplifie compliance management, it will also and align private channels with shared channels, making governance and experience more consistent across Teams. This update promises to increase the support up to 1000 channels per team and 5000 members per channel, removing previous limitations. Teams will also allow meetings to be scheduled directly within private channels, enhancing collaboration.  For organizations using Micr...

502_3 bad gateway IIS AAR RP for Lync

I encountered a "new" error message this week, as I was finalizing a Lync 2013 deployment for a customer. When I say new, it was new to me, as I had not seen this before. Everything was set up for remote access and federations, but certain features, such as mobility did not work right away. I decided to test the URL's from the outside, and was surprised to find the following error message:


This deployment was set up with a IIS ARR for reverse proxy. I searched for the 502 (502.3 to be exact) on forums and internet in general, but could not find any answer to my exact issue.

I verified firewall ports and connectivity was ok. I also checked the web sites on port 4443 and 8080 from a client inside, and saw no apparent errors.

I went through the deployment guide one more time (step by step), and discovered I had forgotten to import the internal CA ROOT to the Reverse Proxy machine. Once this was installed, it all worked just fine.

The reason I decided to write this post, is because the root cause was not very obvious to me (only after reading tracing logs and checking the step by step guide again, was I able to figure out the problem). And I wanted to write a reminder to myself, and maybe help somebody else if they happened to forget to import the ROOT CA.

The 502 "invalid response" can be a lot of things. Certificate error being one of them. Now I know.

For those looking for a guide to set this up, I have two links for you:
This is the one I used: http://uclobby.wordpress.com/2013/08/02/configuring-arr-for-lync-server/

And here is one from nexthop: http://blogs.technet.com/b/nexthop/archive/2013/02/19/using-iis-arr-as-a-reverse-proxy-for-lync-server-2013.aspx

I preferred the first one, as it was a more "general" rule to catch all. But it might not suit all scenarios. The one from nexthop is much more detailed, and will have you set up a rule for each URL.