Thanks for your reply. I did the two things mentioned in your email. I still got the same "page not found" error.
I found one weird log message this morning when I look at one of the cocoon log files such as this one: /dspace/log/cocoon.log.2017-02-12. I don't know what these messages mean. Does it mean what thing went wrong in the DSpace build process. I forgot to mention that I upgraded DSpace from previous 5.2 to current 6.0.
2017-02-12 16:00:02,074 INFO org.apache.cocoon.i18n.XMLResourceBundle - Bundle <file:///usr/share/tomcat/webapps/ROOT/i18n/messages_en_US.xml
> not loaded: Source URI not found
2017-02-12 16:00:02,075 INFO org.apache.cocoon.i18n.XMLResourceBundle - Bundle <file:///usr/share/tomcat/webapps/ROOT/i18n/aspects/Workflow/m
essages_en_US.xml> not loaded: Source URI not found
2017-02-12 16:00:02,075 INFO org.apache.cocoon.i18n.XMLResourceBundle - Bundle <resource://aspects/Workflow/i18n/messages_en_US.xml> not load
ed: Source URI not found
2017-02-12 16:00:02,076 INFO org.apache.cocoon.i18n.XMLResourceBundle - Bundle <file:///usr/share/tomcat/webapps/ROOT/i18n/aspects/Statistics
/messages_en_US.xml> not loaded: Source URI not found
2017-02-12 16:00:02,077 INFO org.apache.cocoon.i18n.XMLResourceBundle - Bundle <resource://aspects/Statistics/i18n/messages_en_US.xml> not lo
aded: Source URI not found
...
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I looked over and didn't see "aspects" directory under i18n and couldn't find the file "messages_en_US.xml" at anyplace.