Problem upgrading to 6

I've upgrade to 6.0 using the installer on linux x64. After I've restarted I'm getting the following error and cannot access jira.

2013-05-22 10:25:08,308 localhost-startStop-1 INFO [atlassian.jira.upgrade.UpgradeManagerImpl] Performing Upgrade Task: Converting default Custom field values for User and MultiUser types to store the key of the user rather than the
username.
2013-05-22 10:25:08,308 localhost-startStop-1 ERROR [atlassian.jira.upgrade.UpgradeManagerImpl] Exception thrown during upgrade: java.lang.NullPointerException
com.atlassian.util.concurrent.LazyReference$InitializationException: java.lang.NullPointerException
at com.atlassian.util.concurrent.LazyReference.getInterruptibly(LazyReference.java:149)
at com.atlassian.util.concurrent.LazyReference.get(LazyReference.java:112)
at com.atlassian.util.concurrent.ResettableLazyReference.get(ResettableLazyReference.java:87)
at com.atlassian.jira.issue.fields.CustomFieldImpl.getCustomFieldSearcher(CustomFieldImpl.java:1805)
at com.atlassian.jira.issue.fields.CustomFieldImpl.<init>(CustomFieldImpl.java:247)
at com.atlassian.jira.issue.fields.CustomFieldImpl.<init>(CustomFieldImpl.java:222)
at com.atlassian.jira.issue.managers.DefaultCustomFieldManager$CustomFieldCache.cloneCustomFields(DefaultCustomFieldManager.java:730)
at com.atlassian.jira.issue.managers.DefaultCustomFieldManager$CustomFieldCache.getAllCustomFields(DefaultCustomFieldManager.java:717)
at com.atlassian.jira.issue.managers.DefaultCustomFieldManager$CopyOnWriteCustomFieldCache.getAllCustomFields(DefaultCustomFieldManager.java:621)
at com.atlassian.jira.issue.managers.DefaultCustomFieldManager.getAllCustomFields(DefaultCustomFieldManager.java:417)
at com.atlassian.jira.issue.managers.DefaultCustomFieldManager.getCustomFieldObjects(DefaultCustomFieldManager.java:412)
at com.atlassian.jira.upgrade.tasks.UpgradeTask_Build6045.getCustomFields(UpgradeTask_Build6045.java:132)
at com.atlassian.jira.upgrade.tasks.UpgradeTask_Build6045.doUpgrade(UpgradeTask_Build6045.java:59)
at com.atlassian.jira.upgrade.UpgradeManagerImpl.doUpgradeTaskSuccess(UpgradeManagerImpl.java:673)
at com.atlassian.jira.upgrade.UpgradeManagerImpl.runUpgradeTasks(UpgradeManagerImpl.java:526)
at com.atlassian.jira.upgrade.UpgradeManagerImpl.doUpgrade(UpgradeManagerImpl.java:456)
at com.atlassian.jira.upgrade.UpgradeManagerImpl.doUpgradeIfNeeded(UpgradeManagerImpl.java:399)
at com.atlassian.jira.upgrade.UpgradeManagerImpl.doUpgradeIfNeededAndAllowed(UpgradeManagerImpl.java:333)
at com.atlassian.jira.upgrade.UpgradeLauncher.checkIfUpgradeNeeded(UpgradeLauncher.java:100)
at com.atlassian.jira.upgrade.UpgradeLauncher.start(UpgradeLauncher.java:49)
at com.atlassian.jira.startup.DefaultJiraLauncher$3.run(DefaultJiraLauncher.java:117)
at com.atlassian.jira.config.database.DatabaseConfigurationManagerImpl.doNowOrEnqueue(DatabaseConfigurationManagerImpl.java:315)
at com.atlassian.jira.config.database.DatabaseConfigurationManagerImpl.doNowOrWhenDatabaseActivated(DatabaseConfigurationManagerImpl.java:209)
at com.atlassian.jira.startup.DefaultJiraLauncher.postDbLaunch(DefaultJiraLauncher.java:105)
at com.atlassian.jira.startup.DefaultJiraLauncher.access$100(DefaultJiraLauncher.java:30)
at com.atlassian.jira.startup.DefaultJiraLauncher$1.run(DefaultJiraLauncher.java:69)
at com.atlassian.jira.util.devspeed.JiraDevSpeedTimer.run(JiraDevSpeedTimer.java:33)
at com.atlassian.jira.startup.DefaultJiraLauncher.start(DefaultJiraLauncher.java:64)
at com.atlassian.jira.startup.LauncherContextListener.contextInitialized(LauncherContextListener.java:54) <+5> (StandardContext.java:4791) (StandardContext.java:5285) (LifecycleBase.java:150) (ContainerBase.java:1559) (ContainerBase.java:1549)
at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NullPointerException
at com.atlassian.jira.util.JiraUtils.loadComponent(JiraUtils.java:96)
at com.atlassian.jira.util.JiraUtils.loadComponent(JiraUtils.java:91)
at com.atlassian.jira.issue.managers.DefaultCustomFieldManager.loadSearcher(DefaultCustomFieldManager.java:286)
at com.atlassian.jira.issue.managers.DefaultCustomFieldManager.getCustomFieldSearcher(DefaultCustomFieldManager.java:273)
at com.atlassian.jira.issue.fields.CustomFieldImpl$CustomFieldSearcherLazyRef.create(CustomFieldImpl.java:2099)
at com.atlassian.util.concurrent.ResettableLazyReference$InternalReference.create(ResettableLazyReference.java:140)
at com.atlassian.util.concurrent.LazyReference$Sync.run(LazyReference.java:321)
at com.atlassian.util.concurrent.LazyReference.getInterruptibly(LazyReference.java:143)
at com.atlassian.util.concurrent.LazyReference.get(LazyReference.java:112)
at com.atlassian.util.concurrent.ResettableLazyReference.get(ResettableLazyReference.java:87)
at com.atlassian.jira.issue.fields.CustomFieldImpl.getCustomFieldSearcher(CustomFieldImpl.java:1805)
at com.atlassian.jira.issue.fields.CustomFieldImpl.<init>(CustomFieldImpl.java:247)
at com.atlassian.jira.issue.fields.CustomFieldImpl.<init>(CustomFieldImpl.java:222)
at com.atlassian.jira.issue.managers.DefaultCustomFieldManager$CustomFieldCache.cloneCustomFields(DefaultCustomFieldManager.java:730)
at com.atlassian.jira.issue.managers.DefaultCustomFieldManager$CustomFieldCache.getAllCustomFields(DefaultCustomFieldManager.java:717)
at com.atlassian.jira.issue.managers.DefaultCustomFieldManager$CopyOnWriteCustomFieldCache.getAllCustomFields(DefaultCustomFieldManager.java:621)
at com.atlassian.jira.issue.managers.DefaultCustomFieldManager.getAllCustomFields(DefaultCustomFieldManager.java:417)
at com.atlassian.jira.issue.managers.DefaultCustomFieldManager.getCustomFieldObjects(DefaultCustomFieldManager.java:412)
at com.atlassian.jira.issue.CustomFieldManager$getCustomFieldObjects.call(Unknown Source)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:42)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:108)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:112)
at com.onresolve.jira.groovy.ScriptManagerImpl.createIndexingCustomField(ScriptManagerImpl.groovy:466) <+3>
at java.lang.reflect.Method.invoke(Unknown Source)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1054)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnCurrentN(ScriptBytecodeAdapter.java:78)
at com.onresolve.jira.groovy.ScriptManagerImpl.this$dist$invoke$1(ScriptManagerImpl.groovy)
at com.onresolve.jira.groovy.ScriptManagerImpl$1.methodMissing(ScriptManagerImpl.groovy) <+3>
at java.lang.reflect.Method.invoke(Unknown Source)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
at groovy.lang.MetaClassImpl.invokeMissingMethod(MetaClassImpl.java:811)
at groovy.lang.MetaClassImpl.invokePropertyOrMissing(MetaClassImpl.java:1103)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1056)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:884)
at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.callCurrent(PogoMetaClassSite.java:66)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:46)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:133)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:137)
at com.onresolve.jira.groovy.ScriptManagerImpl$1.run(ScriptManagerImpl.groovy:392)
... 1 more