Similar to the core bug JENKINS-17125.

Also happens with textfinder plugin on LTS 1.509.3.
Manage Old Data gives list of entries of with:
Type: hudson.model.FreeStyleProject
Error: MissingFieldException: No field 'completeBuild' found in class 'hudson.model.Result', MissingFieldException: No field 'completeBuild' found in class 'hudson.model.Result', CannotResolveClassException: hudson.plugins.textfinder.TextFinderPublisher

Trying to discard will generate NPE:
Caused by: java.lang.NullPointerException
at hudson.model.AbstractItem.getRootDir(AbstractItem.java:162)
at hudson.model.Items.getConfigFile(Items.java:236)
at hudson.model.AbstractItem.getConfigFile(AbstractItem.java:461)
at hudson.model.AbstractItem.save(AbstractItem.java:456)
at hudson.model.Job.save(Job.java:152)
at hudson.model.AbstractProject.save(AbstractProject.java:268)
at hudson.diagnosis.OldDataMonitor.doDiscard(OldDataMonitor.java:275)

Seems like it might be a duplicate of https://issues.jenkins-ci.org/browse/JENKINS-18809

@esinsag no, keep JENKINS-18809 for the Claim plugin please, and if you have some issue with the Text Finder plugin file it separately and link.

Code changed in jenkins
User: Jesse Glick
Path:
pom.xml
src/main/java/com/sonyericsson/hudson/plugins/metadata/cli/CliUtils.java
src/main/java/com/sonyericsson/hudson/plugins/metadata/contributors/BuildContributorsController.java
src/main/java/com/sonyericsson/hudson/plugins/metadata/model/MetadataBuildAction.java
http://jenkins-ci.org/commit/metadata-plugin/0dc90f1ab6b3942b971d76d3732c45dfb0c9fa0a
Log:
[FIXED JENKINS-20950] Do not try to persist the build which holds this action.

Code changed in jenkins
User: Robert Sandell
Path:
pom.xml
src/main/java/com/sonyericsson/hudson/plugins/metadata/cli/CliUtils.java
src/main/java/com/sonyericsson/hudson/plugins/metadata/contributors/BuildContributorsController.java
src/main/java/com/sonyericsson/hudson/plugins/metadata/model/MetadataBuildAction.java
src/test/java/com/sonyericsson/hudson/plugins/metadata/cli/CliUtilsTest.java
src/test/java/com/sonyericsson/hudson/plugins/metadata/search/MetadataViewJobFilterTest.java
http://jenkins-ci.org/commit/metadata-plugin/60e54b20648e205cff20cb5fd154b81ea827813c
Log:
Merge pull request #2 from jglick/RunAction2-JENKINS-20950

JENKINS-20950 Use RunAction2

Compare: https://github.com/jenkinsci/metadata-plugin/compare/2842fd93fd1f...60e54b20648e

Not sure if the PR I submitted actually addresses the issue here. From the stack trace, it looks like the Saveable reported to have a problem was a FreeStyleProject, not a FreeStyleBuild. That would potentially implicate MetadataJobAction, yet this does not seem to save any inappropriate references; it is a bit weird that it saves a side reference to the MetadataJobProperty, but neither should save a reference to the Job which would be the dangerous thing.

I was trying to reproduce a similar situation in a functional test to explore whether OldDataMonitor could be made to behave more gracefully in this situation:

@Test public void savingOrphanedBuild() throws Exception {
    FreeStyleProject p = r.createFreeStyleProject("p");
    FreeStyleBuild b = p.scheduleBuild2(0).get();
    BogusAction a = new BogusAction();
    a.build = b;
    p._getRuns().purgeCache();
    b = p.getBuildByNumber(1);
    b.addAction(a);
    b.save();
    System.out.println(FileUtils.readFileToString(new File(b.getRootDir(), "build.xml")));
}
public static final class BogusAction extends InvisibleAction {
    Run build;
}

This produces a malformed build.xml similar to that reported for JENKINS-17125. But this is not an error condition to load, and even if it were made so (using Run.XSTREAM2.alias to deliberately break the loading of BogusAction after a reload) I would guess that OldDataMonitor.discard would be saving the Run, and doing so would not result in the NPE caused by a missing AbstractItem.parent.

Code changed in jenkins
User: Jesse Glick
Path:
core/src/main/java/hudson/diagnosis/OldDataMonitor.java
test/src/test/java/hudson/diagnosis/OldDataMonitorTest.java
test/src/test/resources/hudson/diagnosis/OldDataMonitorTest/robustness.zip
http://jenkins-ci.org/commit/jenkins/8508fc365ac9faa4fa6ccee116e820c0455f0988
Log:
JENKINS-19544 Whether or not we manage to save an object with old data, be sure to remove it from the list, and continue with other objects.
Otherwise a bug like JENKINS-20950 can prevent anything from being saved, and holds references to all the old data.