Neo4j 5 Error Messages

Recently we noticed some customers having these types of warning messages in their debug.log file:

WARN  [o.n.i.p.PageCache] Reflection access to java.nio.DirectByteBuffer is not available, using fallback mode. This could have negative impact on performance and memory usage. Consider adding --add-opens=java.base/java.nio=ALL-UNNAMED to VM options.

WARN  [o.n.k.i.t.l.f.LogFileChannelNativeAccessor] [neo4j/93245d0a] Unable to evict transaction log from cache with version: xxxx. Error: ErrorCode=-1, errorMessage='Incorrect file descriptor.'

WARN  [o.n.k.i.t.l.f.LogFileChannelNativeAccessor] [neo4j/93245d0a] Error on attempt to preallocate log file version: xxx. Error: ErrorCode=-1, errorMessage='Incorrect file descriptor.'

These warnings occur if these additional jvm settings are missing from the neo4j.conf.

server.jvm.additional=--add-opens=java.base/java.nio=ALL-UNNAMED
server.jvm.additional=--add-opens=java.base/java.io=ALL-UNNAMED
server.jvm.additional=--add-opens=java.base/sun.nio.ch=ALL-UNNAMED

This would impair the ability of the JVM to manage memory when it became contentious and as a result you see errors begin to appear in the logs and potentially a degradation in overall performance as the JVM begins to operate sub-optimally.

If you are using a Docker deployment, check to make sure you are properly including the additional JVM settings. For a docker deployment:
“Variables that can take multiple options, such as NEO4J_server_jvm_additional, must be defined just once, and include a concatenation of the multiple values.”

If you are deploying in other ways, check the neo4j.conf to make sure those lines are in the configuration.