Connection errors in Power Automate mean the flow can't authenticate to one of the services it's trying to use — Outlook, SharePoint, Teams, or a third-party connector. The fix is almost always re-authorizing the connection, but knowing exactly which connection is broken and why saves a lot of time.
1. Find the broken connection in Run History
Go to My Flows, click the failing flow, and open the run that failed. Expand each step to find the one showing a red error. Connection errors typically show messages like "The connection is not valid," "Invalid connection credentials," "The token has expired," or "Access denied." The step name tells you which connector is broken — Outlook, SharePoint, OneDrive, etc.
2. Fix it from the Connections page
Go to Data > Connections (left sidebar in Power Automate). Look for any connection showing a warning or error icon. Click the connection and choose to fix or re-authorize it — this takes you through the sign-in flow for that service again. Once re-authorized, go back to your flow and test it.
Tip: after changing your Microsoft 365 password or going through an MFA reset, all OAuth connections — including Outlook, SharePoint, OneDrive, and Teams — can expire simultaneously. If multiple flows break at once after an account change, this is almost certainly why. Re-authorizing each affected connection resolves them all.
3. If re-authorizing doesn't fix it
Sometimes a connection gets into a broken state that re-authorization alone doesn't clear. In that case:
- Delete the broken connection from the Connections page
- Open the flow in Edit mode
- Click the step that was failing — it will now prompt you to create a new connection
- Sign in and authorize fresh
- Save and test
4. "Access denied" errors on SharePoint or OneDrive
This is a permissions error, not a connection error — the connection itself is valid, but the account it's connected as doesn't have permission to access that specific site, library, or folder. Check that the account used for the connection (the one you signed into when creating the flow) has at least Edit access to the SharePoint site or OneDrive location the flow is trying to use.
5. Flows failing after the original owner leaves
Connections in Power Automate are tied to the user who created them. When someone leaves and their account is disabled or deleted, all flows using their connections break — even if you've transferred flow ownership. The fix is to open each affected flow, delete the broken connection steps, and reconnect them using an active account. In organizations where this is recurring, consider using a dedicated service account (a shared mailbox or functional account that doesn't belong to a specific person) to own connections for business-critical flows.
6. Connector throttling / "Too many requests"
If your flow runs frequently and calls a connector many times, you may hit API limits that cause intermittent failures with "Too many requests" or 429 errors. This isn't a broken connection — it's rate limiting. Fixes include:
- Adding a Delay action between repeated calls to space them out
- Using filter queries on your data source rather than retrieving everything and filtering in the flow, which reduces the number of API calls
- Upgrading your Power Automate license if you're consistently hitting limits on business-critical flows
7. Third-party connector failures
Connectors to non-Microsoft services (Slack, Google Drive, Salesforce, etc.) can fail when the third-party service updates its API or revokes tokens. Check the third-party service's own status page if the connection consistently fails even after re-authorization — the issue may be on their end, not Microsoft's.
The bottom line
The large majority of Power Automate connection errors come down to expired tokens after an account or password change — re-authorizing the connection from the Connections page fixes them. For recurring failures on shared flows, switching to a dedicated service account for connections prevents the same problem after every staff change.