We have a flow that posts an adaptive card to a non-private channel that's suddenly started failing. It worked on Feb. 10th 2026 but on today's run (Feb. 24 2026) it started giving the below error on the Teams post action (it is posting as the flow bot since there's no User option for the adaptive card post). The workflows app is allowed in Teams admin center, installed in the channel, and the account being used is a Team member.
The request failed. Error code: 'InstallFlowTeamsAppRequestFailed'. Error Message: 'Failed to install the Power Automate app in Microsoft Teams for team with ID '95efb2ca-4935-4c05-b0e6-ad85b5359ab7'. Please try adding the Power Automate app to this team directly from the Microsoft Teams client. Error details: '{"error":{"code":"Forbidden","message":"Bulk Membership operation PUT failed on user '28:509e64f1-1e70-4744-91dc-3bba3977d3e2' with response code 207, status code :'AclCheckFailed', subStatusCode'1'","innerError":{"code":"AccessDenied","message":"Bulk Membership operation PUT failed on user '28:509e64f1-1e70-4744-91dc-3bba3977d3e2' with response code 207, status code :'AclCheckFailed', subStatusCode'1'","details":[],"date":"2026-02-24T16:43:35","request-id":"3658c149-6bab-437a-9525-133546585bbd","client-request-id":"14e61913-e1e5-403e-bdc2-6b1a1d4a9d68"}}}''.