I can't get trigger in bookings to work

Copper Contributor

Today suddenly my trigger in Power Automate on bookings came up with an error.

That means if you choose the standard trigger like this it can't select any booking page:




Copy of the error below:


Could not retrieve values. The dynamic invocation request failed with error: "Failed to get onbehalfof access token: connectionId=microsoftbookings, message={\"error\":\"invalid_grant\",\"error_description\":\"AADSTS50013: Assertion failed signature validation. [Reason - Key was found, but use of the key to verify the signature failed., Thumbprint of key used by client: '5D1BE4A3C3FB03751A5929D4EDB33D9D3D0C8E10', Found key 'Start=02/08/2024 17:02:53, End=02/08/2029 17:02:53', Please visit the Azure Portal, Graph Explorer or directly use MS Graph to see configured keys for app Id '00000000-0000-0000-0000-000000000000'. Review the documentation at https://docs.microsoft.com/en-us/graph/deployments to determine the corresponding service endpoint and https://docs.microsoft.com/en-us/graph/api/application-get?view=graph-rest-1.0&tabs=http to build a query request URL, such as 'https://graph.microsoft.com/beta/applications/00000000-0000-0000-0000-000000000000']. Trace ID: 6293da83-d121-4a3a-b227-aa5b8165bd00 Correlation ID: 94209883-5861-46b8-b4ec-4ca17cd86f59 Timestamp: 2024-03-04 15:45:52Z\",\"error_codes\":[50013],\"timestamp\":\"2024-03-04 15:45:52Z\",\"trace_id\":\"6293da83-d121-4a3a-b227-aa5b8165bd00\",\"correlation_id\":\"94209883-5861-46b8-b4ec-4ca17cd86f59\",\"error_uri\":\"https://login.windows.net/error?code=50013\"}".


My connection is fine so any suggestions on how it can be fixed to work again?




9 Replies
Same issue here. Microsoft, please help!

Same here. Any advice so far? @Antonio Bibovski 

Mine strangely started working after I pasted the full URL of the booking page into the trigger as a custom value. I mean, it didn't work with that, but afterwards my booking page was suddenly selectable. Weird.

The error message you're seeing indicates an issue with the authentication process when trying to retrieve values from the Microsoft Bookings API. Specifically, it seems there's a problem with the assertion signature validation, which is related to the security keys used for authentication.

To resolve this issue, you can try the following steps:

Check Key Configuration: Verify that the security keys (also known as client secrets) configured for your Microsoft Bookings API application in the Azure Portal are correct and have not expired. You may need to regenerate the key if it has expired or is no longer valid.

Update Authentication Settings: Ensure that the authentication settings in your Power Automate flow or Microsoft Bookings API application are correctly configured to use the updated security keys.

Reauthorize Connections: Reauthorize the connection to the Microsoft Bookings API in your Power Automate flow to refresh the authentication tokens and ensure they are using the correct security keys.

Check Service Status: Sometimes, issues like this can be caused by temporary service outages or maintenance. Check the service status of the Microsoft Bookings API to ensure it is operational.

If the issue persists after trying these steps, you may need to reach out to Microsoft support for further assistance, as they can provide more specific guidance based on your application's configuration and the error message you're encountering.

@Senthil Gopal 


how you you register the ID's from the Azure app registrations in PowerAutomate for the 'newly created' booking connector? 


Or is there a way to see the (existing?) booking connector in Azure and update the permissions for the registration?

Would the right Graph Permissions in the Azure app registration not be set by by default when creating a new booking connector in PowerAutomate?


To register the IDs from the Azure app registrations in Power Automate for a newly created booking connector, you can follow these steps:

  1. Register the Azure App:

    • Go to the Azure portal and navigate to Azure Active Directory.
    • Select "App registrations" and click on "New registration."
    • Follow the prompts to register the app. Note down the Application (client) ID and Directory (tenant) ID.
  2. Add API Permissions:

    • In the Azure portal, go to your app registration.
    • Click on "API permissions" and then "Add a permission."
    • Select the Microsoft Graph API and the required permissions for the booking connector.
    • Grant admin consent for these permissions if necessary.
  3. Configure Power Automate Connector:

    • In Power Automate, create a new flow or edit an existing one.
    • Add the "Bookings" connector to your flow.
    • When prompted, sign in using the Azure account associated with the app registration.
    • Use the Application (client) ID and Directory (tenant) ID obtained earlier to authenticate the connector.
  4. Set Graph Permissions:

    • Ensure that the correct Graph permissions are set in the Azure app registration for the booking connector.
    • If the permissions are not set correctly, update them in the Azure portal.
  5. Update Permissions for Existing Connector:

    • If you need to update permissions for an existing booking connector in Power Automate, you can do so by modifying the API permissions in the Azure app registration and then re-authenticating the connector in Power Automate.
  6. Verification:

    • Test your flow in Power Automate to ensure that the connector is working correctly and has the necessary permissions.

The correct Graph permissions should be set by default when creating a new booking connector in Power Automate. However, you may need to verify and update these permissions if necessary.

@Senthil Gopal i did actually find an easier way...
when you select integrations in your booking page, chose power automate, then there is an smtp address displayed. copy that address, then follow link "go to setup" to switch to power automate (note :a connection is created in the background by that step)



then in the flow, configure the (e.g. "appointment") connection, but instead of waiting for the drop down to populate, select "enter custom value", and then copy that email address from the step before into the field.

I expect that resembles the AzureID for the application that was registered in the background.



Voila! ;)

That worked for me too! I pasted in the email address of the booking page and it works. I was also able to then select afterwards. Seems like a bug to wake up the connector
That worked perfectly for me. After I tested it, I was then able to go back and select from any of our booking pages as expected.