Online migration fails for RSA-DM 6.0.2 to Rhapsody DM 6.0.5

  I am upgrading RSA-DM 6.0.2 to Rhapsody DM 6.0.5. During Online migration step i am getting errors. The log shows following errors.

2018-04-08 17:05:53,889 [     DM Upgrade Manager Thread] []  INFO com.ibm.xtools.rmps.frontservice.jaf.upgrade.DMUpgradeManager  - Upgrade Step 7 Running: Upgrade User Domains. <o:p> </o:p>

2018-04-08 17:05:53,975 [     DM Upgrade Manager Thread] [] ERROR com.ibm.xtools.rmps.frontservice.jaf.upgrade.DMUpgradeManager  - java.lang.NullPointerException <o:p> </o:p>

            at com.ibm.xtools.rmps.dtk.setup.DTKConfiguration.getSnapshotIdBySnapshotName(DTKConfiguration.java:1093) <o:p> </o:p>

            at com.ibm.xtools.rmps.dtk.setup.DTKConfiguration.installUserDomain(DTKConfiguration.java:1029) <o:p> </o:p>

            at com.ibm.xtools.rmps.dtk.setup.DTKConfiguration.upgradeUserDomains(DTKConfiguration.java:1006) <o:p> </o:p>

            at com.ibm.xtools.rmps.dtk.setup.upgrade.UpgradeUserDomains.performUpgrade(UpgradeUserDomains.java:37) <o:p> </o:p>

            at com.ibm.xtools.rmps.frontservice.jaf.upgrade.DMUpgradeManager.executeUpgradeExtension(DMUpgradeManager.java:398) <o:p> </o:p>

            at com.ibm.xtools.rmps.frontservice.jaf.upgrade.DMUpgradeManager.access$2(DMUpgradeManager.java:375) <o:p> </o:p>

            at com.ibm.xtools.rmps.frontservice.jaf.upgrade.DMUpgradeManager$1.run(DMUpgradeManager.java:335) <o:p> </o:p>

            at com.ibm.xtools.rmps.frontservice.jaf.common.internal.threads.DMThread.run(DMThread.java:54) <o:p> </o:p>

2018-04-08 17:05:53,975 [     DM Upgrade Manager Thread] [] ERROR com.ibm.xtools.rmps.frontservice.jaf.upgrade.DMUpgradeManager  - Upgrade Step 7 Aborted: Upgrade User Domains. <o:p> </o:p>

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