IdleTimeoutConduit MissingFormatArgumentException: Format specifier '%s'

After the idle timeout expires I receive the following error:

XNIO000011: Task io.undertow.conduits.IdleTimeoutConduit$1@1941255e failed with an exception

java.util.MissingFormatArgumentException: Format specifier '%s'
at java.util.Formatter.format(Formatter.java:2519) ~[na:1.8.0_66]
at java.util.Formatter.format(Formatter.java:2455) ~[na:1.8.0_66]
at java.lang.String.format(String.java:2940) ~[na:1.8.0_66]
at org.jboss.logging.Slf4jLocationAwareLogger.doLogf(Slf4jLocationAwareLogger.java:81) ~[jboss-logging-3.3.0.Final.jar!/:3.3.0.Final]
at org.jboss.logging.Logger.logf(Logger.java:2445) ~[jboss-logging-3.3.0.Final.jar!/:3.3.0.Final]
at org.jboss.logging.DelegatingBasicLogger.tracef(DelegatingBasicLogger.java:119) ~[jboss-logging-3.3.0.Final.jar!/:3.3.0.Final]
at io.undertow.conduits.IdleTimeoutConduit$1.run(IdleTimeoutConduit.java:72) ~[undertow-core-1.3.14.Final.jar!/:1.3.14.Final]
at org.xnio.nio.WorkerThread.safeRun(WorkerThread.java:580) ~[xnio-nio-3.3.4.Final.jar!/:3.3.4.Final]
at org.xnio.nio.WorkerThread.run(WorkerThread.java:464) ~[xnio-nio-3.3.4.Final.jar!/:3.3.4.Final]