stablyai/orca · warning · BrowserError

browser_tab_changed

browser_tab_changed

Error message

Browser page ${target.browserPageId} changed while evaluating; retry the command

What it means

Thrown by evaluate() after a successful Runtime.evaluate when re-resolving the command target shows the browserPageId now maps to a different webContentsId than when the command started — the tab navigated to a new page or was replaced during eval. The message explicitly instructs retry. This guards against returning a result computed in a now-stale page context.

Source

Thrown at src/main/browser/agent-browser-bridge.ts:1583

          releaseDebugger = acquireElectronDebugger(wc).release
          const { result, exceptionDetails } = (await wc.debugger.sendCommand('Runtime.evaluate', {
            expression,
            returnByValue: true,
            awaitPromise: true
          })) as {
            result: { value?: unknown; description?: string }
            exceptionDetails?: { text: string; exception?: { description?: string } }
          }
          if (exceptionDetails) {
            throw new BrowserError(
              'browser_eval_error',
              exceptionDetails.exception?.description ?? exceptionDetails.text
            )
          }

          const currentTarget = this.resolveCommandTarget(worktreeId, target.browserPageId)
          if (currentTarget.webContentsId !== target.webContentsId) {
            throw new BrowserError(
              'browser_tab_changed',
              `Browser page ${target.browserPageId} changed while evaluating; retry the command`
            )
          }
          return {
            result:
              result.value !== undefined
                ? typeof result.value === 'object' && result.value !== null
                  ? JSON.stringify(result.value)
                  : String(result.value)
                : (result.description ?? ''),
            origin: wc.getURL()
          }
        } catch (error) {
          if (error instanceof BrowserError) {
            throw error
          }
          if (!this.getWebContents(target.webContentsId)) {

View on GitHub (pinned to 1136503c6a)

Solutions

Retry the evaluate command — the message explicitly says 'retry the command' and the new target will be current.
If the page is prone to navigation, wait for a stable URL/load event before issuing the eval.
For SPA flows, use a wait(url/load) before evaluate to ensure the page has settled.

Defensive patterns

Strategy: retry

Type guard

function isTabChangedError(e: unknown): boolean {
  return e instanceof BrowserError && e.code === 'browser_tab_changed'
}

Try / catch

for (let attempt = 0; attempt < 2; attempt++) {
  try {
    return await bridge.evaluate(expression, worktreeId, browserPageId)
  } catch (e) {
    if (e instanceof BrowserError && e.code === 'browser_tab_changed' && attempt === 0) continue
    throw e
  }
}

Prevention

Call wait({ load: 'load' }) or wait({ url }) before evaluate on navigation-prone pages
Avoid issuing click/navigate and evaluate back-to-back on the same tab without a settle
Track navigation state and only evaluate when the page is stable

When it happens

Trigger: evaluate() captures target.webContentsId, sends Runtime.evaluate (which awaits the promise), and during that await the page navigates (SPAroute change, redirect, or full navigation) causing resolveCommandTarget to return a different webContentsId for the same browserPageId. SPA navigations that swap the WebContents, or client-side redirects, trigger this.

Common situations: Evaluating an expression on a page that auto-redirects (login flows, meta-refresh); SPA route transitions mid-eval; the agent issued a click that triggered navigation while an eval was in flight; tab replacement (e.g. prerender activation).

Related errors

AI-assisted analysis of stablyai/orca@1136503c6a (2026-08-12). Data as JSON: /api/errors/71d148749eecc0af. Report an issue: GitHub.