Index: openacs-4/packages/acs-lang/www/admin/lookup.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-lang/www/admin/lookup.tcl,v
diff -u -r1.2.6.1 -r1.2.6.2
--- openacs-4/packages/acs-lang/www/admin/lookup.tcl	10 Sep 2015 08:21:28 -0000	1.2.6.1
+++ openacs-4/packages/acs-lang/www/admin/lookup.tcl	24 Nov 2016 11:33:15 -0000	1.2.6.2
@@ -17,9 +17,15 @@
         {label "[_ acs-lang.Locale]"}
         {help_text "[_ acs-lang.Can_be_two_character]"}
     }
-} -on_submit {
-    # No substitution
-    set message [lang::message::lookup $locale $key]
+} -on_submit {    
+    if {[catch {
+        # No substitution
+        set message [lang::message::lookup $locale $key]
+    } errmsg]} {
+        ad_return_complaint 1 $errmsg
+        ad_log error $errmsg
+        ad_script_abort
+    }
     
     set keyv [split $key "."]
     set package_key [lindex $keyv 0]