Index: openacs-4/packages/forums/lib/search/search-chunk.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/forums/lib/search/search-chunk.tcl,v
diff -u -r1.9.2.2 -r1.9.2.3
--- openacs-4/packages/forums/lib/search/search-chunk.tcl	13 May 2016 18:21:57 -0000	1.9.2.2
+++ openacs-4/packages/forums/lib/search/search-chunk.tcl	24 May 2016 16:34:50 -0000	1.9.2.3
@@ -20,6 +20,18 @@
         # don't crash interMedia
         regsub -all {[^[:alnum:]_[:blank:]]} $search_text {} search_text
 
+        # replace subsequent spaces
+        regsub -all {\s+} $search_txt " " search_text
+        set search_text [string trim $search_text]
+
+        # don't search for empty search strings
+        if {$search_text eq ""} {
+            set name search_text
+            ad_complain [_ acs-tcl.lt_name_is_not_valid]
+            set messages:rowcount 0
+            return
+        }
+
         set query search_all_forums
         if {$forum_id ne ""} {
             set query search_one_forum