diff --git a/docsource/modules180-190.rst b/docsource/modules180-190.rst
index fd4b86e2175e..f5f098bf583a 100644
--- a/docsource/modules180-190.rst
+++ b/docsource/modules180-190.rst
@@ -698,7 +698,7 @@ Module coverage 18.0 -> 19.0
 +---------------------------------------------------+----------------------+-------------------------------------------------+
 | link_tracker                                      |Nothing to do         |No DB layout changes.                            |
 +---------------------------------------------------+----------------------+-------------------------------------------------+
-| loyalty                                           |                      |                                                 |
+| loyalty                                           |Done                  |                                                 |
 +---------------------------------------------------+----------------------+-------------------------------------------------+
 | lunch                                             |                      |                                                 |
 +---------------------------------------------------+----------------------+-------------------------------------------------+
diff --git a/openupgrade_scripts/scripts/loyalty/19.0.1.0/pre-migration.py b/openupgrade_scripts/scripts/loyalty/19.0.1.0/pre-migration.py
new file mode 100644
index 000000000000..b29087957954
--- /dev/null
+++ b/openupgrade_scripts/scripts/loyalty/19.0.1.0/pre-migration.py
@@ -0,0 +1,37 @@
+from openupgradelib import openupgrade
+
+
+@openupgrade.migrate()
+def migrate(env, version):
+    """Rewrite the removed ``_get_mail_partner`` helper (which returned
+    ``partner_id``, the recipient) to its exact 18.0 equivalent in stored
+    template fields, as the 19.0 data-load render aborts before the existing
+    post-migration could clear the field. ``_get_mail_author`` would swap in
+    the company/internal user instead — wrong partner for custom templates
+    that are never reset by the module update.
+    """
+    for column in ("lang", "partner_to", "email_to", "body_html"):
+        if not openupgrade.column_exists(env.cr, "mail_template", column):
+            continue
+        env.cr.execute(
+            """
+            SELECT data_type FROM information_schema.columns
+             WHERE table_name = 'mail_template' AND column_name = %s
+            """,
+            (column,),
+        )
+        # translated columns (body_html) are jsonb; cast the rewrite back
+        cast = "::jsonb" if env.cr.fetchone()[0] == "jsonb" else ""
+        openupgrade.logged_query(
+            env.cr,
+            f"""
+            UPDATE mail_template
+               SET {column} = REPLACE(
+                   {column}::text,
+                   'object._get_mail_partner()',
+                   'object.partner_id'
+               ){cast}
+             WHERE model = 'loyalty.card'
+               AND {column}::text LIKE '%%_get_mail_partner%%'
+            """,
+        )