It looks like your datanode is trying to start in a secure (Kerberos) mode and you dont have this setup – is that correct?
Can you check that:
hadoop.security.authorization is set to false in all your core-site.xml
And also in the file hadoop-env.sh, comment out the following line
Then restart your datanode process.
Try again and see if you can upload the test again, or check that the error in the Datanode log has been rectified.