Do not Honor (05) is the most common and general message for card transactions that are declined by the Bank. It indicates that the Issuing Bank will not validate the transaction for different reasons.


Some of the most common are: 


  1. The credit card number or expiration date is invalid.
  2. There are insufficient funds in the cardholder's account.
  3. The location or activity is suspicious.
  4. The bank's fraud rules which can take many other factors into consideration.

To resolve this, check to make sure you entered all your data correctly.  If this doesn't resolve the issue, customer needs to contact the Issuing Bank and tell what had happened. Once the problem is solved, customer should be able to transact.



https://www.finance-monthly.com/2018/08/understanding-05-do-not-honor/