Solution
If you are using the Lexmark Smart Card Authentication Client (SCAC), do not update firmware to LW90.xx.P015 instead contact your Lexmark Representative to obtain LW90.xx.P204 or later.
Since firmware update LW90.xx.P015 remains relevant for most users not using SCAC, Lexmark currently does not plan to remove the said update from the support site.
If you have upgraded the printer firmware to LW90.xx.P015 and are now unable to authenticate, please contact support to obtain LW90.xx.P204 or later.