Hey

While I am running the whole process flow of Nutch i.e.
Inject,Generate,Fetch,Parse,Update.

The following errors are being logged:

*Generator Job*

java.lang.Exception: java.lang.ClassCastException:
org.bson.types.ObjectId cannot be cast to java.lang.String
         at
org.apache.hadoop.mapred.LocalJobRunner$Job.runTasks(LocalJobRunner.java:462)
         at
org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:522)
Caused by: java.lang.ClassCastException: org.bson.types.ObjectId cannot
be cast to java.lang.String
         at
org.apache.nutch.crawl.GeneratorMapper.map(GeneratorMapper.java:34)
         at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:145)
         at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:764)
         at org.apache.hadoop.mapred.MapTask.run(MapTask.java:340)
         at
org.apache.hadoop.mapred.LocalJobRunner$Job$MapTaskRunnable.run(LocalJobRunner.java:243)
         at
java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
         at java.util.concurrent.FutureTask.run(FutureTask.java:266)
         at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
         at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
         at java.lang.Thread.run(Thread.java:745)
2017-03-07 15:28:07,696 ERROR crawl.GeneratorJob - GeneratorJob:
java.lang.RuntimeException: job failed: name=[rss_new]generate:
1488880683-1996901673, jobid=job_local78754654_0001
         at
org.apache.nutch.util.NutchJob.waitForCompletion(NutchJob.java:121)
         at org.apache.nutch.crawl.GeneratorJob.run(GeneratorJob.java:233)
         at
org.apache.nutch.crawl.GeneratorJob.generate(GeneratorJob.java:262)
         at org.apache.nutch.crawl.GeneratorJob.run(GeneratorJob.java:328)
         at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
         at org.apache.nutch.crawl.GeneratorJob.main(GeneratorJob.java:336)

*Fetcher Job:*

java.lang.Exception: java.lang.ClassCastException:
org.bson.types.ObjectId cannot be cast to java.lang.String
         at
org.apache.hadoop.mapred.LocalJobRunner$Job.runTasks(LocalJobRunner.java:462)
         at
org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:522)
Caused by: java.lang.ClassCastException: org.bson.types.ObjectId cannot
be cast to java.lang.String
         at
org.apache.nutch.fetcher.FetcherJob$FetcherMapper.map(FetcherJob.java:96)
         at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:145)
         at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:764)
         at org.apache.hadoop.mapred.MapTask.run(MapTask.java:340)
         at
org.apache.hadoop.mapred.LocalJobRunner$Job$MapTaskRunnable.run(LocalJobRunner.java:243)
         at
java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
         at java.util.concurrent.FutureTask.run(FutureTask.java:266)
         at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
         at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
         at java.lang.Thread.run(Thread.java:745)

*Parser Job:*

java.lang.Exception: java.lang.ClassCastException:
org.bson.types.ObjectId cannot be cast to java.lang.String
         at
org.apache.hadoop.mapred.LocalJobRunner$Job.runTasks(LocalJobRunner.java:462)
         at
org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:522)
Caused by: java.lang.ClassCastException: org.bson.types.ObjectId cannot
be cast to java.lang.String
         at
org.apache.nutch.parse.ParserJob$ParserMapper.map(ParserJob.java:80)
         at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:145)
         at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:764)
         at org.apache.hadoop.mapred.MapTask.run(MapTask.java:340)
         at
org.apache.hadoop.mapred.LocalJobRunner$Job$MapTaskRunnable.run(LocalJobRunner.java:243)
         at
java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
         at java.util.concurrent.FutureTask.run(FutureTask.java:266)
         at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
         at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
         at java.lang.Thread.run(Thread.java:745)

The plugin.folder directory specified in conf/nutch-site.xml is correct.
And, when checked in code it point towards the line where the class is
specified.

Like public class GeneratorMapper(). What changes need to be made in the
configuration files.

Thanks and Regards,
Shubham Gupta
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