try:

my $dbh = DBI->connect("DBI:mysql:dbname","roo
t","password", {'RaiseError' => 1 });
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If that still doesn't work, make sure you set up the user correctly in MySQL to allow local access. Log into Mysql and do "select * from user" in the mysql datqabase to see the row corresponding to "root" has "localhost" in the "host" column.