diff --git a/cypress/integration/customize_form.js b/cypress/integration/customize_form.js
index a072240993..bd4564964e 100644
--- a/cypress/integration/customize_form.js
+++ b/cypress/integration/customize_form.js
@@ -10,8 +10,8 @@ context("Customize Form", () => {
 		const naming_rule_default_autoname_map = {
 			"Set by user": "prompt",
 			"By fieldname": "field:",
-			Expression: "format:",
-			"Expression (old style)": "",
+			Expression: "",
+			"Expression (old style)": "format:",
 			Random: "hash",
 			"By script": "",
 		};
diff --git a/frappe/core/doctype/doctype/doctype.py b/frappe/core/doctype/doctype/doctype.py
index 2e2f28349b..9323d7c69f 100644
--- a/frappe/core/doctype/doctype/doctype.py
+++ b/frappe/core/doctype/doctype/doctype.py
@@ -216,6 +216,7 @@ class DocType(Document):
 		self.validate_website()
 		self.validate_virtual_doctype_methods()
 		self.ensure_minimum_max_attachment_limit()
+		self.patch_old_naming_expressions()
 		validate_links_table_fieldnames(self)
 
 		if not self.is_new():
@@ -447,6 +448,18 @@ class DocType(Document):
 				alert=True,
 			)
 
+	def patch_old_naming_expressions(self):
+		if not self.autoname:
+			return
+
+		# We swapped naming_rule field old/new to discourage use of "format:"
+		if self.autoname and self.autoname.startswith("format:"):
+			self.naming_rule = "Expression (old style)"
+			frappe.toast(_("Warning: Usage of 'format:' is discouraged."), indicator="yellow")
+
+		if self.naming_rule == "Expression (old style)" and not self.autoname.startswith("format:"):
+			self.naming_rule = "Expression"
+
 	def change_modified_of_parent(self):
 		"""Change the timestamp of parent DocType if the current one is a child to clear caches."""
 		if frappe.flags.in_import:
diff --git a/frappe/public/js/frappe/doctype/index.js b/frappe/public/js/frappe/doctype/index.js
index 4d8e437c1b..f06ab54876 100644
--- a/frappe/public/js/frappe/doctype/index.js
+++ b/frappe/public/js/frappe/doctype/index.js
@@ -24,6 +24,7 @@ frappe.model.DocTypeController = class DocTypeController extends frappe.ui.form.
 
 	refresh() {
 		this.show_db_utilization();
+		this.remove_old_style_naming_option();
 	}
 
 	show_db_utilization() {
@@ -45,6 +46,12 @@ frappe.model.DocTypeController = class DocTypeController extends frappe.ui.form.
 			});
 	}
 
+	remove_old_style_naming_option() {
+		let df = this.frm.get_docfield("naming_rule");
+		df.options = df.options.replace("Expression (old style)\n", "");
+		this.frm.refresh_field("naming_rule");
+	}
+
 	max_attachments() {
 		if (!this.frm.doc.max_attachments) {
 			return;
@@ -75,8 +82,8 @@ frappe.model.DocTypeController = class DocTypeController extends frappe.ui.form.
 				"Set by user": "prompt",
 				"By fieldname": "field:",
 				'By "Naming Series" field': "naming_series:",
-				Expression: "format:",
-				"Expression (sld style)": "",
+				Expression: "",
+				"Expression (old style)": "format:",
 				Random: "hash",
 				UUID: "UUID",
 				"By script": "",
@@ -99,9 +106,9 @@ frappe.model.DocTypeController = class DocTypeController extends frappe.ui.form.
 			"By fieldname": "Format: <code>field:[fieldname]</code>. Valid fieldname must exist",
 			'By "Naming Series" field':
 				"Format: <code>naming_series:[fieldname]</code>. Default fieldname is <code>naming_series</code>",
-			Expression:
-				"Format: <code>format:EXAMPLE-{MM}morewords{fieldname1}-{fieldname2}-{#####}</code> - Replace all braced words (fieldnames, date words (DD, MM, YY), series) with their value. Outside braces, any characters can be used.",
 			"Expression (old style)":
+				"Format: <code>format:EXAMPLE-{MM}morewords{fieldname1}-{fieldname2}-{#####}</code> - Replace all braced words (fieldnames, date words (DD, MM, YY), series) with their value. Outside braces, any characters can be used.",
+			Expression:
 				"Format: <code>EXAMPLE-.#####</code> Series by prefix (separated by a dot)",
 			Random: "",
 			"By script": "",
@@ -129,9 +136,9 @@ frappe.model.DocTypeController = class DocTypeController extends frappe.ui.form.
 			else if (autoname.startsWith("naming_series:"))
 				this.frm.set_value("naming_rule", 'By "Naming Series" field');
 			else if (autoname.startsWith("format:"))
-				this.frm.set_value("naming_rule", "Expression");
+				this.frm.set_value("naming_rule", "Expression (old style)");
 			else if (autoname === "hash") this.frm.set_value("naming_rule", "Random");
-			else this.frm.set_value("naming_rule", "Expression (old style)");
+			else this.frm.set_value("naming_rule", "Expression");
 
 			setTimeout(() => (this.frm.__from_autoname = false), 500);
 		}