Index: openacs-4/packages/acs-tcl/tcl/membership-rel-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/membership-rel-procs.tcl,v
diff -u -N -r1.11 -r1.11.2.1
--- openacs-4/packages/acs-tcl/tcl/membership-rel-procs.tcl	17 Jan 2019 17:02:00 -0000	1.11
+++ openacs-4/packages/acs-tcl/tcl/membership-rel-procs.tcl	14 Feb 2019 16:15:00 -0000	1.11.2.1
@@ -53,7 +53,7 @@
             if { [ad_conn isconnected] } {
                 set user_id [ad_conn user_id]
             } else {
-                set user_id [db_null]
+                set user_id ""
             }
             db_dml update_modifying_user {}
         }