I have the same issue. It seems to occur on retriggering the same build multiple times (one after another) i.e. the docker images created should be identical.

I also build images in parallel and use docker.build().
java.lang.RuntimeException: Failed to serialize hudson.model.Fingerprint#facets for class hudson.model.Fingerprint
at hudson.util.RobustReflectionConverter$2.writeField(RobustReflectionConverter.java:256)
at hudson.util.RobustReflectionConverter$2.visit(RobustReflectionConverter.java:224)
at com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider.visitSerializableFields(PureJavaReflectionProvider.java:138)
at hudson.util.RobustReflectionConverter.doMarshal(RobustReflectionConverter.java:209)
at hudson.util.RobustReflectionConverter.marshal(RobustReflectionConverter.java:150)
at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:69)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:58)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:43)
at com.thoughtworks.xstream.core.TreeMarshaller.start(TreeMarshaller.java:82)
at com.thoughtworks.xstream.core.AbstractTreeMarshallingStrategy.marshal(AbstractTreeMarshallingStrategy.java:37)
at com.thoughtworks.xstream.XStream.marshal(XStream.java:1026)
at com.thoughtworks.xstream.XStream.marshal(XStream.java:1015)
at com.thoughtworks.xstream.XStream.toXML(XStream.java:988)
at hudson.XmlFile.write(XmlFile.java:170)
at hudson.model.Fingerprint.save(Fingerprint.java:1301)
at hudson.model.Fingerprint.save(Fingerprint.java:1245)
at hudson.BulkChange.commit(BulkChange.java:98)
at org.jenkinsci.plugins.docker.commons.fingerprint.DockerFingerprints.addFromFacet(DockerFingerprints.java:278)
at org.jenkinsci.plugins.docker.workflow.FromFingerprintStep$Execution.run(FromFingerprintStep.java:119)
at org.jenkinsci.plugins.docker.workflow.FromFingerprintStep$Execution.run(FromFingerprintStep.java:75)
at org.jenkinsci.plugins.workflow.steps.AbstractSynchronousNonBlockingStepExecution$1$1.call(AbstractSynchronousNonBlockingStepExecution.java:47)
at hudson.security.ACL.impersonate(ACL.java:260)
at org.jenkinsci.plugins.workflow.steps.AbstractSynchronousNonBlockingStepExecution$1.run(AbstractSynchronousNonBlockingStepExecution.java:44)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.RuntimeException: Failed to serialize org.jenkinsci.plugins.docker.commons.fingerprint.DockerDescendantFingerprintFacet#descendantImageIds for class org.jenkinsci.plugins.docker.commons.fingerprint.DockerDescendantFingerprintFacet
at hudson.util.RobustReflectionConverter$2.writeField(RobustReflectionConverter.java:256)
at hudson.util.RobustReflectionConverter$2.visit(RobustReflectionConverter.java:224)
at com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider.visitSerializableFields(PureJavaReflectionProvider.java:138)
at hudson.util.RobustReflectionConverter.doMarshal(RobustReflectionConverter.java:209)
at hudson.util.RobustReflectionConverter.marshal(RobustReflectionConverter.java:150)
at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:69)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:58)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:43)
at com.thoughtworks.xstream.core.AbstractReferenceMarshaller$1.convertAnother(AbstractReferenceMarshaller.java:88)
at com.thoughtworks.xstream.converters.collections.AbstractCollectionConverter.writeItem(AbstractCollectionConverter.java:64)
at hudson.util.PersistedList$ConverterImpl.marshal(PersistedList.java:237)
at hudson.util.XStream2$AssociatedConverterImpl.marshal(XStream2.java:363)
at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:69)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:58)
at com.thoughtworks.xstream.core.AbstractReferenceMarshaller$1.convertAnother(AbstractReferenceMarshaller.java:84)
at hudson.util.RobustReflectionConverter.marshallField(RobustReflectionConverter.java:265)
at hudson.util.RobustReflectionConverter$2.writeField(RobustReflectionConverter.java:252)
... 27 more
Caused by: java.util.ConcurrentModificationException
at java.util.TreeMap$PrivateEntryIterator.nextEntry(TreeMap.java:1211)
at java.util.TreeMap$KeyIterator.next(TreeMap.java:1265)
at com.thoughtworks.xstream.converters.collections.CollectionConverter.marshal(CollectionConverter.java:73)
at com.thoughtworks.xstream.converters.collections.TreeSetConverter.marshal(TreeSetConverter.java:55)
at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:69)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:58)
at com.thoughtworks.xstream.core.AbstractReferenceMarshaller$1.convertAnother(AbstractReferenceMarshaller.java:84)
at hudson.util.RobustReflectionConverter.marshallField(RobustReflectionConverter.java:265)
at hudson.util.RobustReflectionConverter$2.writeField(RobustReflectionConverter.java:252)
... 43 more
Finished: FAILURE

I've got the same error, same parallel builds.

Not sure if this is the right approach to the problem: https://github.com/jenkinsci/docker-commons-plugin/pull/69

Just wanted to mention.

Code changed in jenkins
User: Björn Häuser
Path:
src/main/java/org/jenkinsci/plugins/docker/commons/fingerprint/DockerFingerprintAction.java
src/main/java/org/jenkinsci/plugins/docker/commons/fingerprint/DockerFingerprints.java
http://jenkins-ci.org/commit/docker-commons-plugin/63f655f11c9be6e79a5f9979dbfa3c2984f3ad2d
Log:
Synchronise on project

I am not sure this makes any sense. I am just trying to solve this
issue: https://issues.jenkins-ci.org/browse/JENKINS-41880

My thoughts:

This is likely caused by changing the finger prints, the finger prints
are scoped to the project (right?). If this is the case synchronising on
the project could make sense. Also `addFromFacet` should not be a
performance killer and rather quick.

The alternative would be for me to synchronise the complete access to the method.

WDYT?

Code changed in jenkins
User: Jesse Glick
Path:
src/main/java/org/jenkinsci/plugins/docker/commons/fingerprint/DockerFingerprints.java
http://jenkins-ci.org/commit/docker-commons-plugin/c38b852d4a9ebff98a0184748396959cdaeba129
Log:
Merge pull request #69 from bjoernhaeuser/synchronise-on-project

JENKINS-41880 Synchronise on Fingerprint

Compare: https://github.com/jenkinsci/docker-commons-plugin/compare/e00c616a8476...c38b852d4a9e
*NOTE:* This service been marked for deprecation: https://developer.github.com/changes/2018-04-25-github-services-deprecation/

Functionality will be removed from GitHub.com on January 31st, 2019.