There's only a single space in "Oct 26" in your test data, but two spaces in your regexp. The following prints "match":

my $date = localtime;
my @fields = split /\s+/, $date;
my $year = pop @fields;
my $month = $fields[1];
my $day = $fields[2];

$_ = "ERROR: tablename      - Description of the error Fri Oct 26 10:1
+2:41 2007";
if ( /^ERROR/ && /$month $day/ ) {
    print "match\n"
}
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Note that // matches against $_ by default.