Most apps permit only 1 active connection from services like Workato to be established, i.e. you can only have 1 active connection to your app via your Workato account.
Your connection can be invalidated/invalidating another connection under these circumstance:
1) You or another Workato user from your company has created another connection to the same user account with the exact same credentials (same user login and password), i.e. a second connection to a SFDC user account will invalidate the first connection to that same SFDC user account.
2) You or another Workato user from your company has created another connection to the same enterprise account with different credentials (different user login and password), i.e. a second connection to a QuickBooks Online enterprise account will invalidate the first connection to that same QuickBooks Online enterprise account.
The fix
If you have an invalidated connection, all you need to do is to reconnect your app to Workato, either in the recipe page or in the Connections page in the menu on the top right corner. However, do keep in mind that if your connection has been invalidated because a new connection was established, you will invalidate this other connection by reconnecting your app, because you are creating a new connection again.
As best practice, we recommend having a special integration user account to manage your connection to Workato, as well as having only 1 integration user per enterprise account.