At least one authentication challenge response could not be sent back to a client. There were %2 of these failures in the ...

At least one authentication challenge response could not be sent back to a client.

There were %2 of these failures in the last %1 minutes. The last one detected was this SIP message:

%3

Cause: This can occur because of low memory conditions, an empty authentication header, or because of underlying failures gathering data or interacting with the security subsystem.
Resolution:
None needed unless the failure count is high (>100). Restart the server if problem persists.