question Error: A JNI error has occurred, please check your installation and try again Exception in thread "main" java.lang.NoClassDefFoundError: com/tinkerpop/blueprints/Graph in Support Questions

Error: A JNI error has occurred, please check your installation and try again Exception in thread "main" java.lang.NoClassDefFoundError: com/tinkerpop/blueprints/Graph

ManjuN — Fri, 30 Oct 2020 07:46:06 GMT

Hi All,

While trying to take Atlas metadata Backup in HDP 3.1.0.0.0-78 using CLI getting below error,

Followed this official link: https://docs.cloudera.com/HDPDocuments/HDP3/HDP-3.1.5/installing-atlas/content/grate_atlas_metadata_when_upgrading_to_hdp-3_0.html

atlas@xxxx-0x00x00xx:~$ python /usr/hdp/3.1.0.0-78/atlas/tools/migration-exporter/atlas_migration_export.py -d /atlas_metadata

Using Java version: 1.8.0_232 and Python 2.7.5

Error: A JNI error has occurred, please check your installation and try again
Exception in thread "main" java.lang.NoClassDefFoundError: com/tinkerpop/blueprints/Graph
at java.lang.Class.getDeclaredMethods0(Native Method)
at java.lang.Class.privateGetDeclaredMethods(Class.java:2701)
at java.lang.Class.privateGetMethodRecursive(Class.java:3048)
at java.lang.Class.getMethod0(Class.java:3018)
at java.lang.Class.getMethod(Class.java:1784)
at sun.launcher.LauncherHelper.validateMainClass(LauncherHelper.java:544)
at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:526)
Caused by: java.lang.ClassNotFoundException: com.tinkerpop.blueprints.Graph
at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:352)
at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
... 7 more

Please help me on this issue,

Thanks in advance

Re: Error: A JNI error has occurred, please check your installation and try again Exception in thread "main" java.lang.NoClassDefFoundError: com/tinkerpop/blueprints/Graph

gul_shad — Tue, 01 Dec 2020 11:21:32 GMT

Hi @ManjuN ,

NoClassDefFoundError Is usually seen when required jar is missing. In this case atlas migration script is looking for a jar which contains class "com/tinkerpop/blueprints/Graph". This class definition is available in blueprints-core-2.6.0.jar which is available on HDP-2.6.x.

# jar -tf /usr/hdp/2.6.<version>/atlas/server/webapp/atlas/WEB-INF/lib/blueprints-core-2.6.0.jar | grep -i "com/tinkerpop/blueprints/Graph" com/tinkerpop/blueprints/Graph.class com/tinkerpop/blueprints/GraphFactory.class com/tinkerpop/blueprints/GraphQuery.class

In your case, you are running a migration script from "3.1.0.0-78" directory and that is the reason you are getting NoClassDefFoundError.

python /usr/hdp/3.1.0.0-78/atlas/tools/migration-exporter/atlas_migration_export.py -d /atlas_metadata

Steps in the document needs to be performed only if you are upgrading your cluster from 2.6.x to 3.0+ version, because In HDP-3.0+, Apache Atlas uses the JanusGraph graph database to store metadata objects whereas in earlier versions, Atlas used the Titan graph database for metadata storage.

The document says, "Before upgrading HDP and Atlas, perform the following steps on the HDP-2.x cluster".

If you are performing this step during a major upgrade (from HDP-2.6.x to HDP3.0+ or 2.6.5 to HDP-7.x), kindly run atlas_migration_export.py script from 2.6.x path. For minor versions, this step is not required.