Cannot add more than 250 members to private Teams channel

Hi Rick, 

Thank you for reaching out and for sharing your concern.  

The confusion is understandable, since the announcement bundles several changes together, but they do not all activate at the same time. 

The 250 to 5,000 member increase depends on your specific channel finishing its migration to the new group mailbox infrastructure, and then on the higher limit reaching that channel. Microsoft confirmed these higher limits only began rolling out in late April 2026, with completion targeted for May 2026, and any channel not yet migrated will not receive the new limits until its migration is complete. Meeting scheduling and the membership increase are delivered through separate phased rollouts, so being able to schedule meetings does not mean the 5,000 limit has reached your channel yet. The expansion applies automatically, with no request or manual enablement needed.  

To confirm your status, your IT administrator can run the PowerShell cmdlet Get-TenantPrivateChannelMigrationStatus, which reports per channel whether migration is complete or pending. If the channel is fully migrated and still capped at 250, the limit increase simply has not finished rolling out and will update on its own. If it is not yet migrated, that is why the old limit still applies, and your IT administrator can follow the steps outlined in the Message Center post MC1134737 in Microsoft 365 admin center to complete the migration and unlock the higher limits. 

I hope you found the answer helpful, and I would greatly appreciate it if you could mark it as accepted. This helps highlight the solution for others who may be searching for similar information in the community. Your contribution not only supports fellow users in finding the right guidance more quickly, but also helps build a more resourceful and collaborative space for everyone. 

Thank you for your kindness and contributions to the forum.   

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