Hi All,

I have the setup using Cassandra backend (Azure Cosmos DB fully managed).

Seems it is not possible to add two edges with the same label.

gremlin> g.addV()
==>v[4288]
gremlin> g.addV()
==>v[4200]
gremlin> g.addV()
==>v[4344]
gremlin> g.addE('child').from(__.V(4288)).to(__.V(4200))
==>e[t4-3b4-t1-38o][4288-child->4200]
gremlin> g.addE('child').from(__.V(4200)).to(__.V(4344))
java.lang.NullPointerException
Type ':help' or ':h' for help.
Display stack trace? [yN]

This is the error in server log

388895 [gremlin-server-exec-7] WARN  org.apache.tinkerpop.gremlin.server.op.AbstractEvalOpProcessor  - Exception processing a script on request [RequestMessage{, requestId=a04edabb-920e-4526-ab3a-1d1d22a8ed82, op='eval', processor='', args={gremlin=g.addE('child').from(__.V(4200)).to(__.V(4344)), userAgent=Gremlin Console/1.21.0, batchSize=64}}].
java.lang.NullPointerException
at org.janusgraph.graphdb.transaction.StandardJanusGraphTx.getUniquenessLock(StandardJanusGraphTx.java:720)
at org.janusgraph.graphdb.transaction.StandardJanusGraphTx.addEdge(StandardJanusGraphTx.java:784)
at org.janusgraph.graphdb.transaction.StandardJanusGraphTx.addEdge(StandardJanusGraphTx.java:774)
at org.janusgraph.graphdb.vertices.AbstractVertex.addEdge(AbstractVertex.java:188)
at org.janusgraph.graphdb.vertices.AbstractVertex.addEdge(AbstractVertex.java:45)
at org.apache.tinkerpop.gremlin.process.traversal.step.map.AddEdgeStartStep.processNextStart(AddEdgeStartStep.java:137)
at org.apache.tinkerpop.gremlin.process.traversal.step.util.AbstractStep.hasNext(AbstractStep.java:150)
at org.apache.tinkerpop.gremlin.process.traversal.util.DefaultTraversal.hasNext(DefaultTraversal.java:222)
at org.apache.tinkerpop.gremlin.server.op.AbstractOpProcessor.handleIterator(AbstractOpProcessor.java:97)
at org.apache.tinkerpop.gremlin.server.op.AbstractEvalOpProcessor.lambda$evalOpInternal$5(AbstractEvalOpProcessor.java:263)
at org.apache.tinkerpop.gremlin.groovy.engine.GremlinExecutor.lambda$eval$0(GremlinExecutor.java:283)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:834)

Does anyone know what could be the problem?

Regards,

Miroslav