Why did I get the “Kernel API returned non-existent relationship type: -1” exception?

In rare situations, the Neo4j Bolt driver throws an IllegalStateException. The top part of the stack appears as: java.lang.IllegalStateException: Kernel API returned non-existent relationship type: -1 at org.neo4j.kernel.impl.factory.GraphDatabaseFacade.getRelationshipTypeById(GraphDatabaseFacade.java:991) Under the covers, this is what happens. The getRelationshipTypeById(int type) method is… Read more →

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Cluster: org.neo4j.kernel.impl.transaction.log.NoSuchTransactionException: Unable to find transaction 1 in any of my logical logs: Couldn’t find any log containing 1

When operating a causal cluster, if “the store” (data/databases/graph.db) is removed from a server that was previously a member of the cluster we will get the following exception when that server is started: java.lang.RuntimeException: Error starting org.neo4j.kernel.impl.factory.GraphDatabaseFacadeFactory, /path/to/neo4j/data/databases/graph.db at org.neo4j.kernel.impl.factory.GraphDatabaseFacadeFactory.initFacade(GraphDatabaseFacadeFactory.java:209)… Read more →

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Recommendations for recovery upon Out Of Memory error

It is possible to configure the JVM (Java Virtual Machine) such that upon encountering an OOM (Out-Of-Memory) error it will force an exception and crash or simply shut down the application. Taking action upon first OOM occurrence can help in… Read more →

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java.lang.OutOfMemoryError: unable to create new native thread

When a client application establishes a session with a Neo4j server via the bolt or bolt+routing protocols, the server allocates a thread to serve as the server-side bolt worker to handle that connection. There is no server-side limitation on the… Read more →

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