Index: openacs-4/packages/xowiki/tcl/xowiki-www-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xowiki/tcl/xowiki-www-procs.tcl,v
diff -u -r1.368.2.147 -r1.368.2.148
--- openacs-4/packages/xowiki/tcl/xowiki-www-procs.tcl	14 Dec 2023 09:57:31 -0000	1.368.2.147
+++ openacs-4/packages/xowiki/tcl/xowiki-www-procs.tcl	20 Dec 2023 11:04:28 -0000	1.368.2.148
@@ -2696,6 +2696,13 @@
     array set containers [list]
     set cc [::${:package_id} context]
 
+    #
+    # Fetching the form data may also affect this object's
+    # variables. Backup the old page object to revert these changes in
+    # case of validation error.
+    #
+    :copy old_page
+
     if {![info exists field_names]} {
       #
       # Field names might come directly from the POST request payload
@@ -2943,6 +2950,13 @@
       foreach f $form_fields {
         $f reset_on_validation_error
       }
+      #
+      # Revert changes performed by this method on the page object, as
+      # these may come from data failing to validate.
+      #
+      foreach var [old_page info vars] {
+        set :$var [old_page set $var]
+      }
     }
 
     #:log "=== get_form_data has validation_errors $validation_errors, instance_attributes: ${:instance_attributes}"