Hi Team!
I hope, you are doing good 
We have released the Hubspot CRM v3 recently. Until the last week, the app works fine. But now we are unable to install or update the app. We have tested this app locally and able to successfully authenticated with Hubspot CRM. Also, we are able to get the access token. We don’t know why this happens.
Could you please look on this and get back to us?
Are you sure that access_token hasn’t expired?
While this is happening can you share with us the logs generated when given $NODE_DEBUG=fdk fdk run command in the terminal?
Summary
Developers had a problem in installation of apps those use OAuth. This issue is caused by the internal team and quickly fix is made live. Hopefully this shouldn’t be problem any more.
@Saravanakumar_Raju, thank you for sharing all the required information, appreciate your activeness.