Hi,
(http://permalink.gmane.org/gmane.comp.misc.koha/36671) mentioned earlier in the Koha general mailing list, I am thinking to downgrade the database structure of Koha 3.16.4 to 3.14.x.
I suggest you to not do this operation, the error is inside this code: Software error:
Can't call method "as_string" on an undefined value at /usr/share/koha/lib/C4/Koha.pm line 1608.
1586 1587 sub NormalizeISBN { 1588 my ($params) = @_; 1589 1590 my $string = $params->{isbn}; 1591 my $strip_hyphens = $params->{strip_hyphens}; 1592 my $format = $params->{format}; 1593 1594 return unless $string; 1595 1596 my $isbn = Business::ISBN->new($string); 1597 1598 if ( $isbn && $isbn->is_valid() ) { 1599 1600 if ( $format eq 'ISBN-10' ) { 1601 $isbn = $isbn->as_isbn10(); 1602 } 1603 elsif ( $format eq 'ISBN-13' ) { 1604 $isbn = $isbn->as_isbn13(); 1605 } 1606 1607 if ($strip_hyphens) { 1608 $string = $isbn->as_string( [] ); 1609 } else { 1610 $string = $isbn->as_string(); 1611 } 1612 1613 return $string; 1614 } 1615 } Probably you have an 020 tag without data or same other problem. To understand better the situation you can try: -- find a search on opac that gives the error -- insert the swith -d in the opac-search.pl -- start opac-search.pl on command line and use perl debugger to find the exact problem Bye