Hi @Stephen Mallin ,
Thanks for reaching out.
This error message is indicating that the audience claim in the token you are providing is not matching the expected audience. The audience claim in the token should match the client ID of the app registration of the API.
You can refer https://learn.microsoft.com/en-us/azure/active-directory/develop/reference-app-manifest#identifieruris-attribute to check supported application ID URI formats.
If your Application ID URI does not start with api:// you'll have to make a manual change to the manifest of your application and switch to access tokens version 2.
Go in manifest of your registered application and change the value of accessTokenAcceptedVersion from null to 2.
Hope this will help.
Thanks,
Shweta
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