Hello myriamj, Your problem's reason can be result of a lot of situations so that you should more details about your code and results. On the other hand if your code run successfully on single cluster you should pay attention about static variables , because your program can't run same JVM on multicluster system so that your static variables can't reachable on another cluster. However if you use single cluster system your code will work successfully because when your program ran on single cluster your mappers will work on same JVM and static fields can be reach. Maybe your solution can be that but you should more detail about your code.
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