We are upgrading from Pega 7.1.6 to Pega 8.4, while running migrate script, we have seen several below errors saying exception thrown when moving PR_ tables and 26 out of 47 are moved successfully. we have verified DB size and grants, roles are given as mentioned in upgrade document. Did anyone face similar issue? 

Error: 

java.util.concurrent.CompletionException: com.pega.pegarules.util.deploy.bulkmover.exception.PegaMigrationRuntimeException: Exception thrown when moving PR_ENGINECLASSES      [java]     at java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:273)      [java]     at java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:280)      [java]     at java.util.concurrent.CompletableFuture$AsyncRun.run(CompletableFuture.java:1629)      [java]     at java.util.concurrent.CompletableFuture$AsyncRun.exec(CompletableFuture.java:1618)      [java]     at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)      [java]     at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)      [java]     at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)      [java]     at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)      [java] Caused by: com.pega.pegarules.util.deploy.bulkmover.exception.PegaMigrationRuntimeException: Exception thrown when moving PR_ENGINECLASSES      [java]     at com.pega.pegarules.util.deploy.bulkmover.ParallelBulkMoverStrategy.waitForTableMove(ParallelBulkMoverStrategy.java:129)      [java]     at com.pega.pegarules.util.deploy.bulkmover.ParallelBulkMoverStrategy.moveOrExcludeTable(ParallelBulkMoverStrategy.java:109)      [java]     at com.pega.pegarules.util.deploy.bulkmover.ParallelBulkMoverStrategy.lambda$moveTables$1(ParallelBulkMoverStrategy.java:54)      [java]     at com.pega.pegarules.util.deploy.bulkmover.ParallelBulkMoverStrategy.lambda$forEachWithThreadPool$2(ParallelBulkMoverStrategy.java:76)      [java]     at java.util.concurrent.CompletableFuture$AsyncRun.run(CompletableFuture.java:1626)      [java]     ... 5 more      [java] Caused by: com.pega.pegarules.util.deploy.bulkmover.exception.PegaMigrationRuntimeException: Failed to load database table PR_ENGINECLASSES      [java]     at com.pega.pegarules.util.deploy.bulkmover.strategy.InMemoryBulkMoverStrategy.moveDatabaseTable(InMemoryBulkMoverStrategy.java:83)      [java]     at com.pega.pegarules.util.deploy.bulkmover.strategy.InMemoryBulkMoverStrategy.lambda$null$2(InMemoryBulkMoverStrategy.java:209)      [java]     at com.pega.pegarules.util.deploy.bulkmover.ConnectionHelper.withConnection(ConnectionHelper.java:135)      [java]     at com.pega.pegarules.util.deploy.bulkmover.ConnectionHelper.withTargetConnection(ConnectionHelper.java:130)      [java]     at com.pega.pegarules.util.deploy.bulkmover.strategy.InMemoryBulkMoverStrategy.lambda$moveDatabaseTable$3(InMemoryBulkMoverStrategy.java:208)      [java]     at com.pega.pegarules.util.deploy.bulkmover.ConnectionHelper.withConnection(ConnectionHelper.java:135)      [java]     at com.pega.pegarules.util.deploy.bulkmover.ConnectionHelper.withSourceConnection(ConnectionHelper.java:126)      [java]     at com.pega.pegarules.util.deploy.bulkmover.strategy.InMemoryBulkMoverStrategy.moveDatabaseTable(InMemoryBulkMoverStrategy.java:207)      [java]     at com.pega.pegarules.util.deploy.bulkmover.ParallelBulkMoverStrategy.lambda$waitForTableMove$4(ParallelBulkMoverStrategy.java:115)      [java]     at java.lang.Thread.run(Thread.java:748)      [java] Caused by: java.sql.BatchUpdateException: ORA-00942: table or view does not exist      [java]      [java]     at oracle.jdbc.driver.OraclePreparedStatement.executeBatch(OraclePreparedStatement.java:11190)      [java]     at oracle.jdbc.driver.OracleStatementWrapper.executeBatch(OracleStatementWrapper.java:244)      [java]     at com.pega.pegarules.util.deploy.bulkmover.strategy.TableLoader.loadRow(TableLoader.java:63)      [java]     at com.pega.pegarules.util.deploy.bulkmover.strategy.InMemoryBulkMoverStrategy.lambda$moveDatabaseTable$1(InMemoryBulkMoverStrategy.java:64)      [java]     at com.pega.pegarules.util.deploy.bulkmover.strategy.TableDumper.forEachRow(TableDumper.java:73)      [java]     at com.pega.pegarules.util.deploy.bulkmover.strategy.InMemoryBulkMoverStrategy.moveDatabaseTable(InMemoryBulkMoverStrategy.java:63)      [java]     ... 9 more