Guarantor search uses Ajax to build patrons search results table. This uses a complex multi escape layers : intranet-tmpl/prog/en/modules/members/tables/guarantor_search.tt : "<a href=\"#\" class=\"btn btn-default btn-xs select_user\" data-borrowernumber=\"[% data.borrowernumber | html %]\">Select</a><input type=\"hidden\" id=\"borrower_data[% data.borrowernumber | html %]\" name=\"borrower_data[% data.borrowernumber | html %]\" value=\"[% To.json(data) | html %]\" />" This is broken if the found guarantor address contains a double quote. I think because it is JSON converted to \" and then html converted to \" which is a non valid JSON.
Marked as dup of bug 22316 (not exactly the same issue, but must be fixed together) *** This bug has been marked as a duplicate of bug 22316 ***