--- loncom/interface/lonprintout.pm	2017/01/29 23:34:58	1.654
+++ loncom/interface/lonprintout.pm	2017/11/12 23:06:10	1.659
@@ -1,7 +1,7 @@
 # The LearningOnline Network
 # Printout
 #
-# $Id: lonprintout.pm,v 1.654 2017/01/29 23:34:58 raeburn Exp $
+# $Id: lonprintout.pm,v 1.659 2017/11/12 23:06:10 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -889,7 +889,7 @@ sub include_pdf {
     my $londocroot = $Apache::lonnet::perlvar{'lonDocRoot'};
     $file =~ s{(.*)/res/}{$londocroot/res/};
 
-    open(FILE,">>$Apache::lonnet::perlvar{'lonPrtDir'}/$env{'user.name'}_$env{'user.domain'}_printout.dat");
+    open(FILE,">>","$Apache::lonnet::perlvar{'lonPrtDir'}/$env{'user.name'}_$env{'user.domain'}_printout.dat");
     print FILE ("$file\n");
     close (FILE);
 
@@ -3452,7 +3452,9 @@ ENDPART
         if ($env{'request.enc'}) {
             $url = &Apache::lonenc::encrypted($url); 
         }
-        $URLback = $url.($url =~ /\?/) ? '&':'?'.'?symb='.$helper->{VARS}{'symb'};
+        if ($url ne '') {
+            $URLback = $url.(($url =~ /\?/) ? '&':'?').'symb='.$helper->{VARS}{'symb'};
+        }
     }
     #
     # Final adjustment of the font size:
@@ -3536,7 +3538,7 @@ ENDPART
 				'cgi.'.$identifier.'.role' => $perm{'pav'},
 				'cgi.'.$identifier.'.numberoffiles' => $#print_array,
 				'cgi.'.$identifier.'.studentnames' => $student_names,
-				'cgi.'.$identifier.'.backref' => $URLback,});
+				'cgi.'.$identifier.'.backref' => &escape($URLback),});
     &Apache::lonnet::appenv({"cgi.$identifier.user"    => $env{'user.name'},
 				"cgi.$identifier.domain"  => $env{'user.domain'},
 				"cgi.$identifier.courseid" => $cnum,