The following error message may appear due to a bug in DBD::mysql (over which the Bugzilla team have no control):

 DBD::Sponge::db prepare failed: Cannot determine NUM_OF_FIELDS at D:/Perl/site/lib/DBD/mysql.pm line 248.
  SV = NULL(0x0) at 0x20fc444
  REFCNT = 1
  FLAGS = (PADBUSY,PADMY)

To fix this, go to <path-to-perl>/lib/DBD/sponge.pm in your Perl installation and replace

 my $numFields;
 if ($attribs->{'NUM_OF_FIELDS'}) {
     $numFields = $attribs->{'NUM_OF_FIELDS'};
 } elsif ($attribs->{'NAME'}) {
     $numFields = @{$attribs->{NAME}};

with

 my $numFields;
 if ($attribs->{'NUM_OF_FIELDS'}) {
     $numFields = $attribs->{'NUM_OF_FIELDS'};
 } elsif ($attribs->{'NAMES'}) {
     $numFields = @{$attribs->{NAMES}};

(note the S added to NAME.)