This error message appears due to the AVS and CSC settings on one of the account configurations of the Blackbaud Merchant Services account. These settings will need to be adjusted in order to manually process a credit card within eTapestry:
  1. Log in into the merchant services portal at https://bbms.blackbaud.com/
  2. Go to Account Management > General Settings
  3. Scroll down to the Account Configurations
  4. Click the 3 dots next to BBMS - eTapestry OFFLINE configuration
  5. Select None in the drop down menu next to CSC Level
  6. Click Save