Index: openacs-4/packages/xowiki/xowiki.info
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xowiki/xowiki.info,v
diff -u -r1.180.2.7 -r1.180.2.8
--- openacs-4/packages/xowiki/xowiki.info	17 Apr 2019 11:57:26 -0000	1.180.2.7
+++ openacs-4/packages/xowiki/xowiki.info	18 Apr 2019 08:07:54 -0000	1.180.2.8
@@ -10,7 +10,7 @@
     <inherit-templates-p>t</inherit-templates-p>
     <auto-mount>xowiki</auto-mount>
 
-    <version name="5.10.0d27" url="http://openacs.org/repository/download/apm/xowiki-5.10.0d27.apm">
+    <version name="5.10.0d28" url="http://openacs.org/repository/download/apm/xowiki-5.10.0d28.apm">
         <owner url="mailto:neumann@wu-wien.ac.at">Gustaf Neumann</owner>
         <summary>A xotcl-based enterprise wiki system with multiple object types</summary>
         <release-date>2017-08-06</release-date>
@@ -55,8 +55,8 @@
         <license>BSD-Style</license>
         <maturity>2</maturity>
 
-        <provides url="xowiki" version="5.10.0d27"/>
-        <requires url="xotcl-core" version="5.10.0d15"/>
+        <provides url="xowiki" version="5.10.0d28"/>
+        <requires url="xotcl-core" version="5.10.0d16"/>
 	<requires url="acs-datetime" version="5.9.1"/>
         <requires url="acs-kernel" version="5.9.1"/>
 	<requires url="acs-tcl" version="5.10.0d22"/>
Index: openacs-4/packages/xowiki/tcl/folder-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xowiki/tcl/folder-procs.tcl,v
diff -u -r1.55.2.3 -r1.55.2.4
--- openacs-4/packages/xowiki/tcl/folder-procs.tcl	28 Feb 2019 12:50:29 -0000	1.55.2.3
+++ openacs-4/packages/xowiki/tcl/folder-procs.tcl	18 Apr 2019 08:07:54 -0000	1.55.2.4
@@ -668,8 +668,13 @@
     }
 
     lassign [split $orderby ,] att order
-    $t orderby -order [expr {$order eq "asc" ? "increasing" : "decreasing"}] $att
-    set resources_list "[$t asHTML]"
+    if {$att in [$t column_names]} {
+      $t orderby -order [expr {$order eq "asc" ? "increasing" : "decreasing"}] $att
+    } else {
+      ad_log warning "Ignore invalid sorting criterion '$att'"
+      util_user_message -message "Ignore invalid sorting criterion '$att'"
+    }
+    set resources_list [$t asHTML]
 
     if {$menubar ne ""} {
       set mb [::xowiki::MenuBar new -id submenubar]
Index: openacs-4/packages/xowiki/tcl/includelet-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xowiki/tcl/includelet-procs.tcl,v
diff -u -r1.239.2.6 -r1.239.2.7
--- openacs-4/packages/xowiki/tcl/includelet-procs.tcl	22 Mar 2019 13:16:42 -0000	1.239.2.6
+++ openacs-4/packages/xowiki/tcl/includelet-procs.tcl	18 Apr 2019 08:07:54 -0000	1.239.2.7
@@ -4050,14 +4050,17 @@
     lassign [split $orderby ,] att order
     set sortable 1
     if {$att ni $field_names} {
-      if {[ns_conn isconnected]} {
-        set user_agent [string tolower [ns_set get [ns_conn headers] User-Agent]]
-        if {[string match "*bingbot*" $user_agent] || [string match "*turnitin*" $user_agent]} {
-          # search engines like bingbot might still have old buggy pages in their indices;
-          # don't generate errors on non existing attributes starting with "__*"
-          set sortable 0
-        }
-      }
+      # if {[ns_conn isconnected]} {
+      #   set user_agent [string tolower [ns_set get [ns_conn headers] User-Agent]]
+      #   if {[string match "*bingbot*" $user_agent] || [string match "*turnitin*" $user_agent]} {
+      #     # search engines like bingbot might still have old buggy pages in their indices;
+      #     # don't generate errors on non existing attributes starting with "__*"
+      #     set sortable 0
+      #   }
+      # }
+      ad_log warning "Ignore invalid sorting criterion '$att'"
+      util_user_message -message "Ignore invalid sorting criterion '$att'"
+      set sortable 0
     }
     if {$sortable} {
       if {$att eq "_page_order"} {
@@ -4816,7 +4819,7 @@
         }}
       } -instproc render {} {
         :get_parameters
-        if {[info commands ::dotlrn_community::get_community_id] ne ""} { 
+        if {[info commands ::dotlrn_community::get_community_id] ne ""} {
           set community_id [::dotlrn_community::get_community_id]
           set base_url [dotlrn_community::get_community_url $community_id]