The problem is solved by an input whose sourcetype is set to automatic, most likely from a file or directory input.
http://docs.splunk.com/Documentation/Splunk/6.2.2/Data/Bypassautomaticsourcetypeassignment
However, in 6.2+ I am not seeing a way to set sourcetype to automatic when setting up new data inputs. Best thing I can suggest is too do two things:
Run: $SPLUNK_HOME/bin/cmd btool inputs list --debug to display all inputs and try to determine erroneous sources of data, disable or modify where necessary.
Move $SPLUNk_HOME/etc/apps/learned/local/props.conf and $SPLUNk_HOME/etc/apps/learned/local/sourcetypes.conf to a temp directory and restart Splunk.
This was successful for me today. Hope this helps - Good Luck!
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