Error in migrating OWL data into GRAKN - vaticle-typeql

Question

I am trying to migrate a OWL data into GRAKN using the migration script as described here. I started my GRAKN engine and then executed ./migration.sh owl -i /home/file1.owl -k grakn but I get this error:
Migrating data /home/file1.owl using Grakn Engine localhost:4567 into graph grakn
Exception in thread "main" java.lang.RuntimeException: java.lang.IllegalArgumentException: Graph Factory [ai.grakn.factory.TitanInternalFactory] is not valid
at ai.grakn.factory.FactoryBuilder.newFactory(FactoryBuilder.java:101)
at ai.grakn.factory.FactoryBuilder.getGraknGraphFactory(FactoryBuilder.java:82)
at ai.grakn.factory.FactoryBuilder.getFactory(FactoryBuilder.java:62)
at ai.grakn.factory.GraknSessionImpl.configureGraphFactoryRemote(GraknSessionImpl.java:153)
at ai.grakn.factory.GraknSessionImpl.configureGraphFactory(GraknSessionImpl.java:134)
at ai.grakn.factory.GraknSessionImpl.getConfiguredFactory(GraknSessionImpl.java:90)
at ai.grakn.factory.GraknSessionImpl.open(GraknSessionImpl.java:79)
at ai.grakn.migration.owl.Main.runOwl(Main.java:64)
at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:184)
at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:175)
at java.util.Collections$2.tryAdvance(Collections.java:4717)
at java.util.Collections$2.forEachRemaining(Collections.java:4725)
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151)
at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174)
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:418)
at ai.grakn.migration.owl.Main.main(Main.java:52)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at ai.grakn.factory.FactoryBuilder.newFactory(FactoryBuilder.java:99)
... 19 more
Caused by: java.lang.IllegalArgumentException: Could not instantiate implementation: com.thinkaurelius.titan.diskstorage.cassandra.astyanax.AstyanaxStoreManager
at com.thinkaurelius.titan.util.system.ConfigurationUtil.instantiate(ConfigurationUtil.java:55)
at com.thinkaurelius.titan.diskstorage.Backend.getImplementationClass(Backend.java:473)
at com.thinkaurelius.titan.diskstorage.Backend.getStorageManager(Backend.java:407)
at com.thinkaurelius.titan.graphdb.configuration.GraphDatabaseConfiguration.<init>(GraphDatabaseConfiguration.java:1325)
at com.thinkaurelius.titan.core.TitanFactory.open(TitanFactory.java:94)
at com.thinkaurelius.titan.core.TitanFactory.open(TitanFactory.java:84)
at com.thinkaurelius.titan.core.TitanFactory$Builder.open(TitanFactory.java:139)
at ai.grakn.factory.TitanInternalFactory.configureGraph(TitanInternalFactory.java:113)
at ai.grakn.factory.TitanInternalFactory.newTitanGraph(TitanInternalFactory.java:88)
at ai.grakn.factory.TitanInternalFactory.buildTinkerPopGraph(TitanInternalFactory.java:84)
at ai.grakn.factory.TitanInternalFactory.buildTinkerPopGraph(TitanInternalFactory.java:60)
at ai.grakn.factory.AbstractInternalFactory.getTinkerPopGraph(AbstractInternalFactory.java:141)
at ai.grakn.factory.AbstractInternalFactory.getTinkerPopGraph(AbstractInternalFactory.java:135)
at ai.grakn.factory.AbstractInternalFactory.getGraph(AbstractInternalFactory.java:110)
at ai.grakn.factory.AbstractInternalFactory.open(AbstractInternalFactory.java:95)
at ai.grakn.factory.SystemKeyspace.loadSystemOntology(SystemKeyspace.java:114)
at ai.grakn.factory.FactoryBuilder.newFactory(FactoryBuilder.java:107)
at ai.grakn.factory.FactoryBuilder.getGraknGraphFactory(FactoryBuilder.java:82)
at ai.grakn.factory.AbstractInternalFactory.getSystemFactory(AbstractInternalFactory.java:80)
at ai.grakn.factory.AbstractInternalFactory.<init>(AbstractInternalFactory.java:74)
at ai.grakn.factory.TitanInternalFactory.<init>(TitanInternalFactory.java:64)
... 24 more
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.thinkaurelius.titan.util.system.ConfigurationUtil.instantiate(ConfigurationUtil.java:44)
... 44 more
Caused by: com.thinkaurelius.titan.diskstorage.TemporaryBackendException: Temporary failure in storage backend
at com.thinkaurelius.titan.diskstorage.cassandra.astyanax.AstyanaxStoreManager.ensureKeyspaceExists(AstyanaxStoreManager.java:580)
at com.thinkaurelius.titan.diskstorage.cassandra.astyanax.AstyanaxStoreManager.<init>(AstyanaxStoreManager.java:291)
... 49 more
Is there any mistake in the command I am executing to do the migration? What can I do to resolve this issue?
UPDATE: I was able to resolve the above issue but now I am getting following error in trying to start the graql shell:
Exception in thread "graql-session-0" java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextNode(HashMap.java:1437)
at java.util.HashMap$ValueIterator.next(HashMap.java:1466)
at ai.grakn.graph.internal.AbstractGraknGraph.loadOntologyCacheIntoTransactionCache(AbstractGraknGraph.java:337)
at ai.grakn.graph.internal.AbstractGraknGraph.getConceptLog(AbstractGraknGraph.java:307)
at ai.grakn.graph.internal.AbstractGraknGraph.buildType(AbstractGraknGraph.java:450)
at ai.grakn.graph.internal.AbstractGraknGraph.getTypeByLabel(AbstractGraknGraph.java:548)
at ai.grakn.graph.internal.AbstractGraknGraph.getMetaConcept(AbstractGraknGraph.java:608)
at ai.grakn.engine.session.GraqlSession.getTypes(GraqlSession.java:371)
at ai.grakn.engine.session.GraqlSession.sendTypes(GraqlSession.java:348)
at ai.grakn.engine.session.GraqlSession.lambda$new$48(GraqlSession.java:105)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)