Nullpointer exception in hashmap when running nutch on a hadoop cluster

Nullpointer exception in hashmap when running nutch on a hadoop cluster

I run nutch crawler on a hadoop cluster with only 2 node, but when i ran
nutch job on hadoop i get a nullpointer exception after "update-table"
phase,
the specific error comes below
Exception in thread "main" java.lang.NullPointerException
at java.util.Hashtable.put(Hashtable.java:394)
at java.util.Properties.setProperty(Properties.java:143)
at org.apache.hadoop.conf.Configuration.set(Configuration.java:419)
at org.apache.nutch.indexer.IndexerJob.createIndexJob(IndexerJob.java:128)
at org.apache.nutch.indexer.solr.SolrIndexerJob.run(SolrIndexerJob.java:44)
at org.apache.nutch.crawl.Crawler.runTool(Crawler.java:68)
at org.apache.nutch.crawl.Crawler.run(Crawler.java:192)
at org.apache.nutch.crawl.Crawler.run(Crawler.java:250)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
at org.apache.nutch.crawl.Crawler.main(Crawler.java:257)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.util.RunJar.main(RunJar.java:160)
i'm newbie in hadoop and nutch and don't know where to look.
i use hadoop-1.2.0 and nutch 2.2.1.
i ran nutch crawler by this command
~/hadoop-1.2.0/bin/hadoop jar apache-nutch-2.2.1.job
org.apache.nutch.crawl.Crawler -solr http://10.1.1.69:8090/solr/core1/
urls -depth 1 -topN 1 -batch 111