We have recently updated our Netsuite connector, and you will need to obtain an application ID from Netsuite to verify your credentials on Workato. To do so, log in as Administrator to Netsuite, then in Setup, go to Integration > Manage Integrations. If you do not have any integrations set up yet, you can create a new one, and name it Workato. You will also need to check the USER CREDENTIALS checkbox as shown below.
Following that, if you have an existing connection with Netsuite, you will need to go to your connections page and edit your netsuite connection, and you should now see this new field "Application ID. Copy and paste the your application ID that you have just found/created into that field, and your connections should be working properly again. If you are creating a new Netsuite connection, you will also need to find the Application ID, and fill up the rest of the fields as you normally would.