IssueEvent causes IllegalArgumentException to be thrown: java.lang.IllegalArgumentException: No event type with id X

I've just upgraded from 3.4.2 to 3.6.1. Most things work fine. However when IssueEvents are fired (created , updated ,assigned, resolved, closed, commented, reopened, deleted, moved, worklogged, workstarted, workstopped, genericevent), IllegalArgumentException is thrown by these three listeners: IssueIndexListener, IssueCacheListner and MailListener and logged in catalina.out as follows:

2006-05-15 15:40:19,468 ERROR [jira.event.issue.IssueEventDispatcher] Exception thrown from listener [com.atlassian.jira.event.listeners.search.IssueIndexList
ener] : No event type with id 9
java.lang.IllegalArgumentException: No event type with id 9

2006-05-15 15:40:19,470 ERROR [jira.event.issue.IssueEventDispatcher] Exception thrown from listener [com.atlassian.jira.event.listeners.mail.MailListener] :
No event type with id 9
java.lang.IllegalArgumentException: No event type with id 9

2006-05-15 15:40:19,471 ERROR [jira.event.issue.IssueEventDispatcher] Exception thrown from listener [com.atlassian.jira.event.listeners.cache.IssueCacheListe
ner] : No event type with id 9
java.lang.IllegalArgumentException: No event type with id 9

at com.atlassian.jira.event.type.DefaultEventTypeManager.getEventType(DefaultEventTypeManager.java:100)
at com.atlassian.jira.event.issue.AbstractIssueEventListener.workflowEvent(AbstractIssueEventListener.java:91)
at com.atlassian.jira.event.issue.IssueEventDispatcher.dispatchEvent(IssueEventDispatcher.java:105)
at com.atlassian.jira.event.issue.IssueEventDispatcher.dispatchEvent(IssueEventDispatcher.java:80)
at com.atlassian.jira.event.issue.IssueEventDispatcher.dispatchEvent(IssueEventDispatcher.java:67)
at com.atlassian.jira.web.action.issue.MoveIssueConfirm.issueUpdate(MoveIssueConfirm.java:265)
at com.atlassian.jira.web.action.issue.MoveIssueConfirm.doExecute(MoveIssueConfirm.java:224)
at webwork.action.ActionSupport.execute(ActionSupport.java:153)
at com.atlassian.jira.action.JiraActionSupport.execute(JiraActionSupport.java:58)
at webwork.dispatcher.GenericDispatcher.executeAction(GenericDispatcher.java:132)
.
.
.
Is this a bug with jira in this release?