diff --git a/assets/js/components/Config/DeviceModal/DeviceModalBase.vue b/assets/js/components/Config/DeviceModal/DeviceModalBase.vue
index f855f7967..b20fbf4e6 100644
--- a/assets/js/components/Config/DeviceModal/DeviceModalBase.vue
+++ b/assets/js/components/Config/DeviceModal/DeviceModalBase.vue
@@ -512,6 +512,11 @@ export default defineComponent({
 		},
 		values: {
 			handler() {
+				// a prior test result no longer matches the edited config:
+				// revert "Save anyway" back to "Validate & save"
+				if (this.test.isError || this.test.isSuccess) {
+					this.test = initialTestState();
+				}
 				this.updateServiceValues();
 			},
 			deep: true,
@@ -689,7 +694,6 @@ export default defineComponent({
 					this.testDevice,
 					this.$refs["form"] as HTMLFormElement
 				);
-				console.log("test result", success);
 				if (!success) {
 					return;
 				}
diff --git a/tests/config-required-field.spec.ts b/tests/config-required-field.spec.ts
new file mode 100644
index 000000000..3ed3801a7
--- /dev/null
+++ b/tests/config-required-field.spec.ts
@@ -0,0 +1,56 @@
+import { test, expect } from "@playwright/test";
+import { start, stop, baseUrl } from "./evcc";
+import { expectModalVisible } from "./utils";
+
+test.use({ baseURL: baseUrl() });
+
+const templateFlags = [
+  "--disable-auth",
+  "--template-type",
+  "meter",
+  "--template",
+  "tests/config-required-field.tpl.yaml",
+];
+
+test.beforeEach(async () => {
+  await start(undefined, undefined, templateFlags);
+});
+test.afterEach(async () => {
+  await stop();
+});
+
+test.describe("required field validation", async () => {
+  // regression test for evcc-io/evcc#29919: clearing a required field after a
+  // failed connection test must not allow saving via the "Save anyway" button
+  test("cannot save with empty required field after failed test", async ({ page }) => {
+    await page.goto("/#/config");
+
+    await page.getByRole("button", { name: "Add grid meter" }).click();
+    const meterModal = page.getByTestId("meter-modal");
+    await expectModalVisible(meterModal);
+    await meterModal.getByLabel("Manufacturer").selectOption("Required Field Demo");
+
+    // fill the required field so the connection test runs (and then fails)
+    await meterModal.getByLabel("Secret").fill("some-secret");
+    await meterModal.getByRole("button", { name: "Validate & save" }).click();
+
+    // failed test exposes the "Save anyway" force-save button
+    const forceSave = meterModal.getByRole("button", { name: "Save anyway" });
+    await expect(forceSave).toBeVisible();
+
+    // clearing the field invalidates the stale test result: the button must
+    // revert to "Validate & save" instead of staying in force-save mode
+    await meterModal.getByLabel("Secret").fill("");
+    await expect(forceSave).not.toBeVisible();
+    const validateSave = meterModal.getByRole("button", { name: "Validate & save" });
+    await expect(validateSave).toBeVisible();
+
+    // attempting to save with the empty required field is blocked by validation
+    await validateSave.click();
+    await expectModalVisible(meterModal);
+    await expect(meterModal.getByLabel("Secret")).toHaveJSProperty("validity.valid", false);
+
+    // nothing was persisted
+    await expect(page.getByTestId("grid")).toHaveCount(0);
+  });
+});
diff --git a/tests/config-required-field.tpl.yaml b/tests/config-required-field.tpl.yaml
new file mode 100644
index 000000000..0f3790e26
--- /dev/null
+++ b/tests/config-required-field.tpl.yaml
@@ -0,0 +1,20 @@
+template: required-field-demo
+group: generic
+products:
+  - description:
+      generic: Required Field Demo
+params:
+  - name: usage
+    choice: ["grid"]
+  - name: secret
+    description:
+      generic: Secret
+    required: true
+
+# unreachable uri so the connection test always fails, exposing the
+# "Save anyway" button (see tests/config-required-field.spec.ts)
+render: |
+  type: custom
+  power:
+    source: http
+    uri: http://localhost:1/{{ .secret }}