Index: openacs-4/packages/calendar-portlet/www/calendar-portlet.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/calendar-portlet/www/calendar-portlet.tcl,v
diff -u -N -r1.39.2.1 -r1.39.2.2
--- openacs-4/packages/calendar-portlet/www/calendar-portlet.tcl	17 Apr 2019 19:42:59 -0000	1.39.2.1
+++ openacs-4/packages/calendar-portlet/www/calendar-portlet.tcl	6 Jun 2023 13:39:19 -0000	1.39.2.2
@@ -42,7 +42,12 @@
 # get stuff out of the config array
 array set config $cf
 set view $config(default_view)
-set list_of_calendar_ids $config(calendar_id)
+
+#
+# Cleanup empty strings from the id list
+#
+set list_of_calendar_ids [lsearch -all -inline -not -exact $config(calendar_id) {}]
+
 set calendar_url [ad_conn package_url]calendar/
 
 if {[llength $list_of_calendar_ids] > 1} {