syntax error, unexpected $end, expecting FTS_TEXT or FTS_TERM or FTS_NUMB or '('-Collection of common programming errors

I have many messages like the following in /var/log/mysqld.log What does it mean?

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%$
    syntax error, unexpected $end, expecting FTS_TEXT or FTS_TERM or FTS_NUMB or '('
    syntax error, unexpected $end, expecting FTS_TEXT or FTS_TERM or FTS_NUMB or '('
    syntax error, unexpected $end, expecting FTS_TEXT or FTS_TERM or FTS_NUMB or '('
    syntax error, unexpected $end, expecting FTS_TEXT or FTS_TERM or FTS_NUMB or '('
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%$

centos 6.4 Server version: 5.6.12-56 Percona Server (GPL), Release rc60.4, Revision 393