Step 2: Check Token Refresh Settings in Domains
How does token refresh work?
You have an access token and a refresh token. Both tokens have an expiry time.
In order for access tokens to be automatically refreshed, you need to enable Allow token refresh for your service instance in Oracle Cloud Services. When Allow token refresh is enabled, whenever an integration is running and the access token expires, the refresh token is used to automatically get a new access token. If an integration runs before the access token expires, the access token and refresh token are automatically refreshed. The token expiry time starts again at the maximum amount every time the tokens are refreshed.
If an integration does not run for a while, it's possible for the access token and refresh token to both expire. If that happens, you'll need to manually get a new access token.
Check Token Refresh Settings