“Access denied card: 00000000” means the reader used has a Custom Card Code set inside Card Reader Setup, and the Card being used has a MATCH code of 00000000.
To stop this issue, use a card with a custom MATCH code or disable Custom Card Code.
Disable Custom Card Code
Open the effected reader properties
Select Entry Reader, then Card Reader Setup
Set Custom Card Codes to <None>
Select OK to save