This issue usually occurs when a Power Automate flow or its connection was created using a user account that no longer exists or no longer has access. Removing the user from the department or Entra ID does not automatically update the connections used by existing flows.
To fix this, first open the flow and check the ownership under Details. Remove the old user as an owner and add yourself or a service account. Next, open the flow and look for any trigger or action showing “Connection needs authentication.” Select Change connection and either choose an existing valid connection or create a new one by signing in with the correct account. After updating the connection, open the trigger and reselect the required fields such as site, list, or mailbox, then save the flow. If the trigger still fails, delete it and add it again with the same configuration.
If the flow is part of a Solution, go to the Solution, open Connection references, and update the reference to a valid connection. Finally, turn the flow off, wait a few seconds, and turn it back on to force reauthentication. As a best practice, use service accounts for flow connections and ensure there are multiple owners so flows do not break when users leave.
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