diff --git a/.changeset/yellow-mails-deny.md b/.changeset/yellow-mails-deny.md
new file mode 100644
index 000000000..66b03d1c5
--- /dev/null
+++ b/.changeset/yellow-mails-deny.md
@@ -0,0 +1,5 @@
+---
+"@browserbasehq/stagehand": patch
+---
+
+fix issue where locator.fill() was not working on elements that require direct value setting
diff --git a/packages/core/lib/v3/tests/locator-fill.spec.ts b/packages/core/lib/v3/tests/locator-fill.spec.ts
new file mode 100644
index 000000000..8f19db7e6
--- /dev/null
+++ b/packages/core/lib/v3/tests/locator-fill.spec.ts
@@ -0,0 +1,147 @@
+import { expect, test } from "@playwright/test";
+import { V3 } from "../v3";
+import { StagehandLocatorError } from "../types/public/sdkErrors";
+import { v3TestConfig } from "./v3.config";
+
+test.describe("Locator.fill()", () => {
+ let v3: V3;
+
+ test.beforeEach(async () => {
+ v3 = new V3(v3TestConfig);
+ await v3.init();
+ });
+
+ test.afterEach(async () => {
+ await v3?.close?.().catch((e) => {
+ void e;
+ });
+ });
+
+ test("fills date inputs via value setter even when beforeinput blocks insertText", async () => {
+ const page = v3.context.pages()[0];
+
+ await page.goto(
+ "data:text/html," +
+ encodeURIComponent(
+ `
+
+
+ `,
+ ),
+ );
+
+ const dateInput = page.mainFrame().locator("xpath=/html/body/input");
+ await dateInput.fill("2026-01-01");
+
+ const value = await dateInput.inputValue();
+ expect(value).toBe("2026-01-01");
+ });
+
+ test("xpath case: throws StagehandLocatorError when fill encounters an exception", async () => {
+ const page = v3.context.pages()[0];
+
+ await page.goto(
+ "data:text/html," +
+ encodeURIComponent(
+ `
+
+ `,
+ ),
+ );
+
+ await page.waitForSelector("xpath=/html/body/input");
+
+ await page.evaluate(() => {
+ const input = document.querySelector("input");
+ Object.defineProperty(input, "isConnected", {
+ get() {
+ throw new Error("boom");
+ },
+ });
+ });
+
+ const dateInput = page.mainFrame().locator("xpath=/html/body/input");
+ let error: unknown;
+ try {
+ await dateInput.fill("2026-01-01");
+ } catch (err) {
+ error = err;
+ }
+
+ expect(error).toBeInstanceOf(StagehandLocatorError);
+ if (error instanceof Error) {
+ // Log the message so it's visible in test output.
+ expect(error.message).toContain("Error Filling Element");
+ expect(error.message).toContain("selector: xpath=/html/body/input");
+ expect(error.message).toContain("boom");
+ }
+ });
+
+ test("css selector case: throws StagehandLocatorError when fill encounters an exception", async () => {
+ const page = v3.context.pages()[0];
+
+ await page.goto(
+ "data:text/html," +
+ encodeURIComponent(
+ `
+
+ `,
+ ),
+ );
+
+ await page.waitForSelector("#date");
+
+ // Override in main world
+ await page.evaluate(() => {
+ const input = document.querySelector("input");
+ Object.defineProperty(input, "isConnected", {
+ get() {
+ throw new Error("boom");
+ },
+ configurable: true,
+ });
+ });
+
+ // Also override in the isolated world that CSS selectors use
+ const frameId = page.mainFrameId();
+ const { executionContextId } = await page.sendCDP<{
+ executionContextId: number;
+ }>("Page.createIsolatedWorld", {
+ frameId,
+ worldName: "v3-world",
+ });
+
+ await page.sendCDP("Runtime.evaluate", {
+ expression: `(() => {
+ const input = document.querySelector('input');
+ if (input) {
+ Object.defineProperty(input, 'isConnected', {
+ get() { throw new Error("boom"); },
+ configurable: true
+ });
+ }
+ })()`,
+ contextId: executionContextId,
+ });
+
+ const dateInput = page.mainFrame().locator("#date");
+ let error: unknown;
+ try {
+ await dateInput.fill("2026-01-01");
+ } catch (err) {
+ error = err;
+ }
+
+ expect(error).toBeInstanceOf(StagehandLocatorError);
+ if (error instanceof Error) {
+ expect(error.message).toContain("Error Filling Element");
+ expect(error.message).toContain("selector: #date");
+ expect(error.message).toContain("boom");
+ }
+ });
+});
diff --git a/packages/core/lib/v3/types/public/sdkErrors.ts b/packages/core/lib/v3/types/public/sdkErrors.ts
index ca8443c26..b41653c59 100644
--- a/packages/core/lib/v3/types/public/sdkErrors.ts
+++ b/packages/core/lib/v3/types/public/sdkErrors.ts
@@ -161,6 +161,14 @@ export class StagehandDomProcessError extends StagehandError {
}
}
+export class StagehandLocatorError extends StagehandError {
+ constructor(action: string, selector: string, message: string) {
+ super(
+ `Error ${action} Element with selector: ${selector} Reason: ${message}`,
+ );
+ }
+}
+
export class StagehandClickError extends StagehandError {
constructor(message: string, selector: string) {
super(
diff --git a/packages/core/lib/v3/understudy/locator.ts b/packages/core/lib/v3/understudy/locator.ts
index b5c32cb29..16c317b26 100644
--- a/packages/core/lib/v3/understudy/locator.ts
+++ b/packages/core/lib/v3/understudy/locator.ts
@@ -3,12 +3,17 @@ import { Protocol } from "devtools-protocol";
import * as fs from "fs";
import * as os from "os";
import * as path from "path";
-import { locatorScriptSources } from "../dom/build/locatorScripts.generated";
+import {
+ locatorScriptBootstrap,
+ locatorScriptGlobalRefs,
+ locatorScriptSources,
+} from "../dom/build/locatorScripts.generated";
import type { Frame } from "./frame";
import { FrameSelectorResolver, type SelectorQuery } from "./selectorResolver";
import {
StagehandElementNotFoundError,
StagehandInvalidArgumentError,
+ StagehandLocatorError,
ElementNotVisibleError,
} from "../types/public/sdkErrors";
import { normalizeInputFiles } from "./fileUploadUtils";
@@ -510,6 +515,8 @@ export class Locator {
*/
async fill(value: string): Promise {
const session = this.frame.session;
+ // Use the bundled locator globals; the raw fill snippet depends on helper symbols.
+ const fillDeclaration = `function(value) { ${locatorScriptBootstrap}; return ${locatorScriptGlobalRefs.fillElementValue}.call(this, value); }`;
const { objectId } = await this.resolveNode();
let releaseNeeded = true;
@@ -519,11 +526,19 @@ export class Locator {
"Runtime.callFunctionOn",
{
objectId,
- functionDeclaration: locatorScriptSources.fillElementValue,
+ functionDeclaration: fillDeclaration,
arguments: [{ value }],
returnByValue: true,
},
);
+ if (res.exceptionDetails) {
+ // prefer exception.description over text (eg "Uncaught")
+ const message =
+ res.exceptionDetails.exception?.description ??
+ res.exceptionDetails.text ??
+ "Unknown exception during locator().fill()";
+ throw new StagehandLocatorError("Filling", this.selector, message);
+ }
const result = res.result.value as
| { status?: string; reason?: string; value?: string }
diff --git a/packages/core/tests/public-api/public-error-types.test.ts b/packages/core/tests/public-api/public-error-types.test.ts
index 2c110b2d2..5b2849921 100644
--- a/packages/core/tests/public-api/public-error-types.test.ts
+++ b/packages/core/tests/public-api/public-error-types.test.ts
@@ -37,6 +37,7 @@ export const publicErrorTypes = {
StagehandIframeError: Stagehand.StagehandIframeError,
StagehandInitError: Stagehand.StagehandInitError,
StagehandInvalidArgumentError: Stagehand.StagehandInvalidArgumentError,
+ StagehandLocatorError: Stagehand.StagehandLocatorError,
StagehandMissingArgumentError: Stagehand.StagehandMissingArgumentError,
StagehandNotInitializedError: Stagehand.StagehandNotInitializedError,
StagehandResponseBodyError: Stagehand.StagehandResponseBodyError,