===*P*roblem (exception) / *S*olution pairs===
P:Not a known field name:DEFAULT
S: Add plugin
<property>
<name>plugin.includes</name>
<value>query-basic|..... in nutch-default.xml
P: java.lang.NullPointerException at java.io.Reader.(Reader.java:61) ... at org.apache.nutch.analysis.CommonGrams.init(CommonGrams.java:152) at
S: the file common-terms.utf8 needs to be in the right directory (lib | classes?)
<property>
<name>analysis.common.terms.file</name>
<value>common-terms.utf8</value>
<description>The name of a file containing a list of common terms
that should be indexed in n-grams.
</description>
</property>
P: Bad mapred.job.tracker: local
S: if you want to run crawl without hdfs you can omit start-all.sh
just do " nutch crawl urlsdir "
P: ... getlocalpath NullPointerException
S: check mapred.local.dir and other tmp dirs in nutch-default.xml / hadoop-default.xml
P:extension point: org.apache.nutch.net.URLNormalizer does not exist
S:check your plugins + plugin.includes settings and add urlnormalizer-regex or urlnormalizer-(pass|regex|basic)
—
P:java.net.UnknownHostException "hostname"
S: add 127.0.0.1 "hostname" to the /etc/hosts file.
P: ...[null] [MalformedUrlException]
S: add common-terms.utf8 to nutch dir
P: java.lang.ClassCastException: org.apache.hadoop.io.Text
S: wrong hadoop version / patch http://files.pannous.de/org.rar
P:java.lang.NoSuchMethodError: org.apache.hadoop.io.MapFile $Writer.
S: wrong hadoop version / patch http://files.pannous.de/org.rar
P: NullPointerException when crawling :
S: add to nutch-site.xml:
<property>
<name>http.agent.name</name>
<value>NutchCVS</value>
<description>Our HTTP 'User-Agent' request header.</description>
</property>
P: java.io.IOException: config()
S: ignore it ! 
P: nutch crawl ... Job Failed!
S: manifold. set log4j.properties debug level ! log4j.rootLogger=ALL, stdout log4j.appender.stdout=org.apache.log4j.ConsoleAppender
P: No scoring plugins - at least one scoring plugin is required!
S: Add "scoring-opic" to <property> <name>plugin.includes</name>
P: ... java.net.SocketTimeoutException: Accept timed out
S: try using nutch without hdfs / check ports in hadoop file / RPC problems : start crawl without startall.sh ?
P: java.lang.NoClassDefFoundError xyz on windows
S: get rid of spaces in your classpath and path variables !