Index: openacs-4/packages/categories/www/cadmin/category-usage.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/categories/www/cadmin/category-usage.tcl,v
diff -u -r1.10 -r1.11
--- openacs-4/packages/categories/www/cadmin/category-usage.tcl	29 Jun 2018 17:27:18 -0000	1.10
+++ openacs-4/packages/categories/www/cadmin/category-usage.tcl	29 Nov 2019 14:28:48 -0000	1.11
@@ -36,7 +36,7 @@
 set page_title "Objects using category \"$category_name\" of tree \"$tree_name\""
 set url_vars [export_vars -no_empty {category_id tree_id locale object_id}]
 
-set context_bar [category::context_bar $tree_id $locale [value_if_exists object_id]]
+set context_bar [category::context_bar $tree_id $locale [expr {[info exists object_id] ? $object_id : ""}]]
 lappend context_bar "\"$category_name\" Usage"
 
 template::list::create -name items_list -multirow items \