The following error occasionally occurs if for some reason a Jenkins was unable to completely store build data:

Dec 11, 2011 8:46:15 PM org.jvnet.hudson.plugins.thinbackup.ThinBackupPeriodicWork backupNow
SEVERE: Cannot perform a backup. Please be sure jenkins/hudson has write privileges in the configured backup path

.
java.io.FileNotFoundException: Source '/sites/hudson/hudsonHome/jobs/MyJob/builds/2011-12-04_20-31-33' does not exist
at org.apache.commons.io.FileUtils.copyDirectory(FileUtils.java:866)
at org.apache.commons.io.FileUtils.copyDirectory(FileUtils.java:814)
at org.jvnet.hudson.plugins.thinbackup.backup.HudsonBackup.backupBuildsFor(HudsonBackup.java:211)
at org.jvnet.hudson.plugins.thinbackup.backup.HudsonBackup.backupJobs(HudsonBackup.java:180)
at org.jvnet.hudson.plugins.thinbackup.backup.HudsonBackup.backup(HudsonBackup.java:139)
at org.jvnet.hudson.plugins.thinbackup.ThinBackupPeriodicWork.backupNow(ThinBackupPeriodicWork.java:95)
at org.jvnet.hudson.plugins.thinbackup.ThinBackupPeriodicWork.execute(ThinBackupPeriodicWork.java:69)
at org.jvnet.hudson.plugins.thinbackup.hudson.model.AsyncPeriodicWork$1.run(AsyncPeriodicWork.java:58)
at java.lang.Thread.run(Thread.java:619)

I've also seen:

Dec 4, 2011 1:16:41 AM org.jvnet.hudson.plugins.thinbackup.ThinBackupPeriodicWork backupNow
SEVERE: Source '/sites/hudson/hudsonHome/jobs/MyOtherJob/builds/2419' does not exist
java.io.FileNotFoundException: Source '/sites/hudson/hudsonHome/jobs/MyOtherJob/builds/2419' does not exist
at org.apache.commons.io.FileUtils.copyDirectory(FileUtils.java:866)
at org.apache.commons.io.FileUtils.copyDirectory(FileUtils.java:814)
at org.jvnet.hudson.plugins.thinbackup.backup.HudsonBackup.backupBuildsFor(HudsonBackup.java:175)
at org.jvnet.hudson.plugins.thinbackup.backup.HudsonBackup.backupJobs(HudsonBackup.java:148)
at org.jvnet.hudson.plugins.thinbackup.backup.HudsonBackup.backup(HudsonBackup.java:109)
at org.jvnet.hudson.plugins.thinbackup.ThinBackupPeriodicWork.backupNow(ThinBackupPeriodicWork.java:92)
at org.jvnet.hudson.plugins.thinbackup.ThinBackupPeriodicWork.execute(ThinBackupPeriodicWork.java:67)
at hudson.model.AsyncPeriodicWork$1.run(AsyncPeriodicWork.java:51)
at java.lang.Thread.run(Thread.java:619)

These seem to be due to missing files, or invalid symbolic links, but I don't think they should result in the entire ThinBackup backup process terminating, which it does. At least with 1.4 it appears to cancel the shutdown mode, but it doesn't delete old backups and doesn't continue to the next job to backup.

I think it should ignore the error and move on to the next build number/file.