question

Hello Kevin. To start, is the Discover.Response JSON that you're referring to the same as that which was posted in your previous question?

The reason that I ask is that I was able to take the "endpoints" array, which defines the "OLX3" air purifier device, and used that in my own test skill to successfully discover the device. Then, on the "Devices" tab of the Alexa app I tapped on the "OLX3" device to confirm that my skill's back-end Lambda function was receiving a "ReportState" directive every three seconds as one would expect.

Thus, insofar as there is an issue, my initial inclination it that it doesn't have to do with the Discover.Response JSON itself

Next, this comment caught my attention though:

Disabling the skill and reactivating it removes the "error" and everything works normal for a decent amount of time again.

This to me suggests an issue with the skill's account linking implementation. Specifically, that after a user completes account linking, your OAuth server is supposed to provide Amazon with both an access token and a refresh token.

The access token is included in skill requests sent to your skill's back-end, whereas, the refresh token is used by Amazon to get new access tokens from your OAuth server before the access token expires.

If however, the refresh token provided is invalid, or the OAuth server cannot exchange the refresh token for a new auth token, then any skill functionality that requires a valid access token will begin to cease functioning after the access token expires. That is, until the user disables the skill and re-performs account linking again to start the process over.

Indeed, in our Alexa Account Linking Debugging Tips knowledgebase article we have a section titled "Account linking succeeds, but after some time the customer has to link accounts again".

The most common cause of which of which is that "Alexa was unable to use the provided refresh token to grab a new access/refresh token pair." We have the following recommended actions to resolve this:

1. Ensure that the access token time to live (TTL) is more than 5 minutes.
2. Ensure that your authorization server can successfully refresh the access/refresh token pair when presented with a refresh token by Alexa.
3. Ensure that you are not invalidating refresh tokens too early - Alexa may take some time after the access token has expired to refresh the token, and if your authorization server has already invalidated the refresh token, Alexa will not be able to refresh the access/refresh token pair and your customer will have their account linking disabled. More details here:
   • https://developer.amazon.com/docs/alexa/account-linking/requirements-account-linking.html#access-token-uri-requirements

Hey KirkC (and everbody else who might read this),
You were very correct with your obersavation regarding the refresh token.

Our OAuth provider did not issue a refresh token without setting a scope to request a refresh token at all. So there was never a refresh token that could be used in order to get a new access token.

It feels nice to simply (and finally) solve the problem by adding a scope in the alexa skill.

Anyway, Thanks for you help!
Kind regards, Kevin.

PS: Since there was no refresh token at all, could this information be forewarded to the developer that does the debugging somehow? Maybe in the Alexa.Authorization Interface as a warning object in the payload or something. I am in no position to take part in any discussion, just wanted to throw my two cents in here.