The promise was: Barclays Cards (in my case, a store credit card serviced by Barclays) has a new connector with Simplifi (via Plaid) which is supposed to be new, and improved, and awesome!
The reality was: I have tried several days to update my connection, and every time I get the exact same error message: “Something went wrong.” I have waited and re-tried over several days; I have attempted to add it as a new account in Simplifi; and, I have changed my username/password at Barclays. None of these have changed this behavior.