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.)