Q:

Jenkins 2.1: ERROR: Step ‘Post build task’ aborted @ java.nio.charset. MalformedInputException: Input length = 1

After upgrading Jenkins and Plugins recently, the Post Build task randomly aborts with an exception as shown bellow.  What is causing it and how can it be fixed? 
Software Version:
Jenkins ver.  2.103;
Hudson Post build task v1.8
Error Message (printed to Jenkins console):
15:29:38 ERROR: Step ‘Post build task’ aborted due to exception: 
15:29:38 java.nio.charset. MalformedInputException: Input length = 1
15:29:38    at java.nio.charset. CoderResult.throwException(CoderResult.java:281)
15:29:38    at sun.nio.cs. StreamDecoder.implRead(StreamDecoder.java:339)
15:29:38    at sun.nio.cs. StreamDecoder.read(StreamDecoder.java:178)
15:29:38    at java.io. InputStreamReader.read(InputStreamReader.java:184)
15:29:38    at java.io. BufferedReader.fill(BufferedReader.java:161)
15:29:38    at java.io. BufferedReader.read1(BufferedReader.java:212)
15:29:38    at java.io. BufferedReader.read(BufferedReader.java:286)
15:29:38    at hudson. Util.loadFile(Util.java:199)
15:29:38    at hudson.model. Run.getLog(Run.java:1953)
15:29:38    at hudson.plugins.postbuildtask. PostbuildTask.perform(PostbuildTask.java:99)
15:29:38    at hudson.tasks. BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
15:29:38    at hudson.model. AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:744)
15:29:38    at hudson.model. AbstractBuild$AbstractBuildExecution.performAllBuildSteps    (AbstractBuild.java:690)
15:29:38    at hudson.model. Build$BuildExecution.post2(Build.java:186)
15:29:38    at hudson.model. AbstractBuild$AbstractBuildExecution.post(AbstractBuild.java:635)
15:29:38    at hudson.model. Run.execute(Run.java:1752)
15:29:38    at hudson.model. FreeStyleBuild.run(FreeStyleBuild.java:43)
15:29:38    at hudson.model. ResourceController.execute(ResourceController.java:97)
15:29:38    at hudson.model. Executor.run(Executor.java:429)

A:

I believe this is related to JENKINS-49112. 
The problem is that Jenkins cannot handle the charset when reading the console output during runtime.  The breaking changes are reverted and the problem will be resolved in 2.104.