Error When Promoting User to Channel Owner via PowerShell – Teams

Hello everyone,

I'm trying to assign a colleague as an owner of the Teams channels where I am already an owner. I wrote a sequence of PowerShell commands, following the required steps: first adding them to the team as a member, then promoting them to owner, and finally adding them to the channels using the same steps.

There’s no issue adding them to the Teams as a member and then as an owner. Adding them to the channels as a member also works fine. However, I’m unable to assign them as an owner of the channels. I keep getting the same error message, and I haven’t found any documentation or similar error online.

From the Teams interface, I can perform the operation without any issue. However, since I need to do this for several hundred channels, I’m using PowerShell to automate the process.

I’m attaching a screenshot showing the attempt to add them to a single channel, to clearly demonstrate that the issue lies with assigning ownership.

Do you have any idea what might be causing this?

Thanks, and have a great day.