diff --git a/frappe/core/doctype/module_def/module_def.py b/frappe/core/doctype/module_def/module_def.py
index e44fa559df..e00fb853d5 100644
--- a/frappe/core/doctype/module_def/module_def.py
+++ b/frappe/core/doctype/module_def/module_def.py
@@ -26,6 +26,12 @@ class ModuleDef(Document):
 		restrict_to_domain: DF.Link | None
 	# end: auto-generated types
 
+	def validate(self):
+		from frappe.modules.utils import get_module_app
+
+		if not self.app_name and not self.custom:
+			self.app_name = get_module_app(self.name)
+
 	def on_update(self):
 		"""If in `developer_mode`, create folder for module and
 		add in `modules.txt` of app if missing."""
diff --git a/frappe/desk/doctype/workspace/patches/update_app.py b/frappe/desk/doctype/workspace/patches/update_app.py
new file mode 100644
index 0000000000..00b0620c1f
--- /dev/null
+++ b/frappe/desk/doctype/workspace/patches/update_app.py
@@ -0,0 +1,19 @@
+# update app in `Module Def` and `Workspace`
+
+import frappe
+from frappe.modules.utils import get_module_app
+
+
+def execute():
+	for module in frappe.get_all("Module Def", ["name", "app_name"], filters=dict(custom=0)):
+		if not module.app_name:
+			frappe.db.set_value("Module Def", module.name, "app_name", get_module_app(module.name))
+
+	for workspace in frappe.get_all("Workspace", ["name", "module", "app"]):
+		if not workspace.app and workspace.module:
+			frappe.db.set_value(
+				"Workspace",
+				workspace.name,
+				"app",
+				frappe.db.get_value("Module Def", workspace.module, "app_name"),
+			)
diff --git a/frappe/desk/doctype/workspace/workspace.py b/frappe/desk/doctype/workspace/workspace.py
index 05a31af5c1..946dc87451 100644
--- a/frappe/desk/doctype/workspace/workspace.py
+++ b/frappe/desk/doctype/workspace/workspace.py
@@ -85,6 +85,11 @@ class Workspace(Document):
 			if d.link_type == "Report" and d.is_query_report != 1:
 				d.report_ref_doctype = frappe.get_value("Report", d.link_to, "ref_doctype")
 
+		if not self.app and self.module:
+			from frappe.modules.utils import get_module_app
+
+			self.app = get_module_app(self.module)
+
 	def clear_cache(self):
 		super().clear_cache()
 		if self.for_user:
@@ -262,7 +267,7 @@ def new_page(new_page):
 
 	doc = frappe.new_doc("Workspace")
 	doc.title = page.get("title")
-	doc.icon = page.get("icon") or "dashboard"
+	doc.icon = page.get("icon") or "grid"
 	doc.indicator_color = page.get("indicator_color")
 	doc.content = page.get("content")
 	doc.parent_page = page.get("parent_page")
diff --git a/frappe/patches.txt b/frappe/patches.txt
index 3f7c0bcdbc..bcce73ede8 100644
--- a/frappe/patches.txt
+++ b/frappe/patches.txt
@@ -240,3 +240,4 @@ frappe.patches.v16_0.switch_default_sort_order
 frappe.integrations.doctype.oauth_client.patches.set_default_allowed_role_in_oauth_client
 execute:frappe.db.set_single_value("Workspace Settings", "workspace_setup_completed", 1)
 frappe.patches.v16_0.add_app_launcher_in_navbar_settings
+frappe.desk.doctype.workspace.patches.update_app
diff --git a/frappe/public/js/frappe/views/workspace/workspace.js b/frappe/public/js/frappe/views/workspace/workspace.js
index f6ece93445..eea7563bb6 100644
--- a/frappe/public/js/frappe/views/workspace/workspace.js
+++ b/frappe/public/js/frappe/views/workspace/workspace.js
@@ -200,8 +200,13 @@ frappe.views.Workspace = class Workspace {
 
 			let current_page = this.sidebar.all_pages.filter((p) => p.name == page.name)[0];
 			this._page = current_page;
-			let app =
-				this._page.app || frappe.boot.module_app[frappe.router.slug(this._page.module)];
+
+			// set app
+			let app = this._page.app;
+			if (!app && this._page.module) {
+				app = frappe.boot.module_app[frappe.router.slug(this._page.module)];
+			}
+			if (!app) app = "frappe";
 
 			if (typeof current_page.content == "string") {
 				current_page.content = JSON.parse(current_page.content);