Hi @Leila Lei ,
As per this Documentation, Missing of change notification could be because of removal of subscription. Certain events can cause a subscription to be removed:
- User's password has been reset
- User's device is out of compliance
- User's account has been revoked
Depending upon lifecycle notification value you are getting, you can try following suggestions given in the documentation:
- Upon receiving a
subscriptionRemoved
lifecycle notification, the app should recreate the subscription in order to maintain a continuous flow. - On receiving a
missed
lifecycle notification, the app should resynchronize resource data using Microsoft Graph.
Also you can check this document on maximum expiration time of all the resources.
Hope this helps.
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