When taking a slave offline while jobs are running I get the following NPE (I am not sure if this occurs because of fingerprinting because I have another NPE where it does not occur):

11:24:51 Recording fingerprints
11:24:51 Looks like the node went offline during the build. Check the slave log for the details.FATAL: null
11:24:51 java.lang.NullPointerException
11:24:51 at hudson.plugins.timestamper.TimestampFormatter.<init>(TimestampFormatter.java:71)
11:24:51 at hudson.plugins.timestamper.TimestamperConfig$1.get(TimestamperConfig.java:59)
11:24:51 at hudson.plugins.timestamper.TimestamperConfig$1.get(TimestamperConfig.java:54)
11:24:51 at hudson.plugins.timestamper.TimestamperConfig.formatter(TimestamperConfig.java:148)
11:24:51 at hudson.plugins.timestamper.annotator.TimestampAnnotatorFactory.newInstance(TimestampAnnotatorFactory.java:51)
11:24:51 at hudson.console.ConsoleAnnotator._for(ConsoleAnnotator.java:143)
11:24:51 at hudson.console.ConsoleAnnotator.initial(ConsoleAnnotator.java:133)
11:24:51 at hudson.console.AnnotatedLargeText.createAnnotator(AnnotatedLargeText.java:140)
11:24:51 at hudson.console.AnnotatedLargeText.writeHtmlTo(AnnotatedLargeText.java:157)
11:24:51 at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:605)
11:24:51 at hudson.model.Run.execute(Run.java:1557)
11:24:51 at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
11:24:51 at hudson.model.ResourceController.execute(ResourceController.java:88)
11:24:51 at hudson.model.Executor.run(Executor.java:236)

Here is another one for a test job:
11:23:29 Looks like the node went offline during the build. Check the slave log for the details.FATAL: null
11:23:29 java.lang.NullPointerException
11:23:29 at hudson.plugins.timestamper.TimestampFormatter.<init>(TimestampFormatter.java:71)
11:23:29 at hudson.plugins.timestamper.TimestamperConfig$1.get(TimestamperConfig.java:59)
11:23:29 at hudson.plugins.timestamper.TimestamperConfig$1.get(TimestamperConfig.java:54)
11:23:29 at hudson.plugins.timestamper.TimestamperConfig.formatter(TimestamperConfig.java:148)
11:23:29 at hudson.plugins.timestamper.annotator.TimestampAnnotatorFactory.newInstance(TimestampAnnotatorFactory.java:51)
11:23:29 at hudson.console.ConsoleAnnotator._for(ConsoleAnnotator.java:143)
11:23:29 at hudson.console.ConsoleAnnotator.initial(ConsoleAnnotator.java:133)
11:23:29 at hudson.console.AnnotatedLargeText.createAnnotator(AnnotatedLargeText.java:140)
11:23:29 at hudson.console.AnnotatedLargeText.writeHtmlTo(AnnotatedLargeText.java:157)
11:23:29 at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:605)
11:23:29 at hudson.model.Run.execute(Run.java:1557)
11:23:29 at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
11:23:29 at hudson.model.ResourceController.execute(ResourceController.java:88)
11:23:29 at hudson.model.Executor.run(Executor.java:236)