If you are having trouble connecting your Caisse d'Epargne account, it is most likely because you've recently been blocked by the bank for security reasons, due to inserting an invalid code at some point. The message displayed on the end-user's screen is normally (but not exclusively) "truelayer_error".
Please, leave it in standby for two days for the error to expire. Once this period has gone by, try re-connecting.
In the case where the error persists, please share with us the timestamps of both failed attempts (with at least two days difference).