Cannot upload Confluence Backup

After modifying the Confluence backup to change a username, the import fails.

See attached screenshot.

Tested:

1. Flushing Index queue prior to export and import did not affect the behaviour.
2. Modification to the spacekey only worked fine.
3. Normal export and import without modification works fine.
4. Seems to be only related to changing the username.

INFO: Server startup in 19655 ms
org.springframework.jdbc.UncategorizedSQLException: (HibernateTemplate): encountered SQLException [Batch entry 0 insert into INDEXQUEUEENTRIES (CREATIONDATE, TYPE, HANDLE, ENTRYID) values (2007-02-15 15:41:04.264000 +1100, 3, com.atlassian.confluence.pages.Attachment-917511, 360471) was aborted. Call getNextException to see the cause.]; nested exception is java.sql.BatchUpdateException: Batch entry 0 insert into INDEXQUEUEENTRIES (CREATIONDATE, TYPE, HANDLE, ENTRYID) values (2007-02-15 15:41:04.264000 +1100, 3, com.atlassian.confluence.pages.Attachment-917511, 360471) was aborted. Call getNextException to see the cause.
java.sql.BatchUpdateException: Batch entry 0 insert into INDEXQUEUEENTRIES (CREATIONDATE, TYPE, HANDLE, ENTRYID) values (2007-02-15 15:41:04.264000 +1100, 3, com.atlassian.confluence.pages.Attachment-917511, 360471) was aborted. Call getNextException to see the cause.
at org.postgresql.jdbc2.AbstractJdbc2Statement$BatchResultHandler.handleError(AbstractJdbc2Statement.java:2512)
at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1314)
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:347)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeBatch(AbstractJdbc2Statement.java:2574)
at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeBatch(NewProxyPreparedStatement.java:1723)
at net.sf.hibernate.impl.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:54)
at net.sf.hibernate.impl.BatcherImpl.executeBatch(BatcherImpl.java:128)
at net.sf.hibernate.impl.BatcherImpl.prepareStatement(BatcherImpl.java:61)
at net.sf.hibernate.impl.BatcherImpl.prepareStatement(BatcherImpl.java:58)
at net.sf.hibernate.impl.BatcherImpl.prepareBatchStatement(BatcherImpl.java:111)
at net.sf.hibernate.persister.EntityPersister.insert(EntityPersister.java:454)
at net.sf.hibernate.persister.EntityPersister.insert(EntityPersister.java:436)
at net.sf.hibernate.impl.ScheduledInsertion.execute(ScheduledInsertion.java:37)
at net.sf.hibernate.impl.SessionImpl.execute(SessionImpl.java:2449)
at net.sf.hibernate.impl.SessionImpl.executeAll(SessionImpl.java:2435)
at net.sf.hibernate.impl.SessionImpl.execute(SessionImpl.java:2392)
at net.sf.hibernate.impl.SessionImpl.flush(SessionImpl.java:2261)
at net.sf.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:61)
at org.springframework.orm.hibernate.HibernateTransactionManager.doCommit(HibernateTransactionManager.java:472)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:397)
at org.springframework.transaction.interceptor.TransactionAspectSupport.doCloseTransactionAfterThrowing(TransactionAspectSupport.java:279)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:60)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:144)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:174)
at $Proxy48.importAs(Unknown Source)
at com.atlassian.confluence.importexport.actions.ImportLongRunningTask.run(ImportLongRunningTask.java:43)
at java.lang.Thread.run(Thread.java:595)