If you have updated your Bank Activity Provider in R365, pop-ups could appear more often, which is expected. One of those pop-ups may be the following 'Error' modal:
While it appears that an error has occurred, this is not the case. When selecting an account from the Bank Activity screen, the account will automatically be triggered to refresh. The system will often refresh accounts and their connection, so when an account is selected that was recently refreshed, this 'Error' modal may appear to state that the account was updated and does not need to be refreshed again.
Simply click 'Ok' and then retrieve your bank activity.