diff --git a/src/setup/telemetry/setupSentry.ts b/src/setup/telemetry/setupSentry.ts
index e31551b4484d..fded8ed2ca86 100644
--- a/src/setup/telemetry/setupSentry.ts
+++ b/src/setup/telemetry/setupSentry.ts
@@ -57,8 +57,14 @@ function setupSentry(): void {
         integrations,
         environment: CONFIG.ENVIRONMENT,
         release: `${pkg.name}@${pkg.version}`,
-        // UPDATE_REQUIRED is not a real error and makes our errors in Spotnana spike and get rate limited when we bump the app min version, so ignore it
-        ignoreErrors: [CONST.ERROR.UPDATE_REQUIRED],
+        ignoreErrors: [
+            // UPDATE_REQUIRED is not a real error and makes our errors in Spotnana spike and get rate limited when we bump the app min version, so ignore it
+            CONST.ERROR.UPDATE_REQUIRED,
+            // Bare-string rejections from the Convert Experiments script in web/index.html, which reads OnyxDB directly.
+            // They carry no stack frames for thirdPartyErrorFilterIntegration to tag; the prefix limits this to the
+            // browser SDK's rejection wording, so a real Error carrying the same text still reports.
+            /^Non-Error promise rejection captured with value: No data found for key/,
+        ],
         denyUrls: EXTENSION_DENY_URLS,
         beforeSendTransaction: processBeforeSendTransactions,
         enableLogs: true,
diff --git a/tests/unit/setupSentryTest.ts b/tests/unit/setupSentryTest.ts
new file mode 100644
index 000000000000..86c261be177e
--- /dev/null
+++ b/tests/unit/setupSentryTest.ts
@@ -0,0 +1,46 @@
+import setupSentry from '@src/setup/telemetry/setupSentry';
+
+import {stringMatchesSomePattern} from '@sentry/core';
+
+jest.mock('@sentry/react-native', () => ({
+    init: jest.fn(),
+    setTag: jest.fn(),
+}));
+
+jest.mock('@libs/telemetry/integrations', () => ({}));
+
+const sentryMock = jest.requireMock<{init: jest.Mock<void, [{ignoreErrors?: Array<string | RegExp>}]>; setTag: jest.Mock}>('@sentry/react-native');
+
+/** How the browser SDK words a promise rejected with a string. It carries no stack frames, so `ignoreErrors` is the only filter that can match it. */
+function rejectionMessage(reason: string): string {
+    return `Non-Error promise rejection captured with value: ${reason}`;
+}
+
+/** Runs Sentry's own matcher over the patterns setupSentry registered, the way `eventFiltersIntegration` does. */
+function isIgnored(message: string): boolean {
+    const initOptions = sentryMock.init.mock.calls.at(0)?.at(0);
+    if (!initOptions) {
+        throw new Error('setupSentry did not call Sentry.init');
+    }
+
+    return stringMatchesSomePattern(message, initOptions.ignoreErrors ?? []);
+}
+
+describe('setupSentry', () => {
+    beforeEach(() => {
+        jest.clearAllMocks();
+        setupSentry();
+    });
+
+    it('drops the bare-string rejection the Convert Experiments script emits when it reads a missing OnyxDB key', () => {
+        expect(isIgnored(rejectionMessage('No data found for key reportActions_undefined'))).toBe(true);
+    });
+
+    it('keeps unhandled rejections that do not come from that third-party OnyxDB read', () => {
+        expect(isIgnored(rejectionMessage("undefined is not an object (evaluating 'report.reportID')"))).toBe(false);
+    });
+
+    it('keeps a thrown Error carrying the same text, which unlike a bare rejection has a stack to act on', () => {
+        expect(isIgnored('No data found for key reportActions_123')).toBe(false);
+    });
+});