detox device not found after simulator reboot: how to fix

Not specified by the original author.

TL;DR

A rebooted simulator can come back with a new UDID or sit in a half-booted state while Detox still looks for the old device id. List the simulators, boot the right one explicitly, wait until the boot completes, and clear Detox's cached device selection if it persists. Then the run finds its device.

Error

detox device not found after simulator reboot: how to fix

Detox fails with device not found immediately after the simulator reboot step; the simulator exists in Xcode.

Steps

1. List simulators and their states with xcrun simctl list devices. Expected output: you see the target simulator and whether it is Shutdown, Booted, or stuck in between.
2. Boot it explicitly with xcrun simctl boot plus the device UDID, then wait with xcrun simctl bootstatus plus the UDID in blocking mode. Expected output: the device reports as fully booted.
3. If Detox still cannot find it, the UDID changed across the reboot; update the device query in the Detox config to match by name and OS instead of a hardcoded UDID. Expected output: config selects the simulator by stable attributes.
4. Clear Detox build and device caches if a stale selection persists. Expected output: Detox re-discovers devices from scratch.
5. Re-run the test on the freshly booted simulator. Expected output: Detox connects and the suite starts.

When to use

• Detox reports device not found right after a simulator reboot.
• CI reboots simulators between jobs and tests then fail.
• The simulator exists but Detox picks a different one.

When not to use

• The simulator was deleted (recreate it first).
• Android emulator issues (different toolchain, different fix).
• Detox cannot find any simulator ever (check the Xcode and simctl setup).

Variant phrasings

Device stuck in Shutdown state

A reboot that never finished leaves the device Shutdown; boot it explicitly rather than trusting Detox to do it.

Detox picks the wrong simulator

Name plus OS matching beats UDID matching across reboots; pin the query, not the id.

CI simulator never boots

CI images sometimes need the simulator runtime installed or the bootstatus wait added; check the image contents.

Why it happens

Detox resolves the target device once and caches the choice, while a reboot can change the simulator's identity or leave it mid-boot. The mismatch is between Detox's cached device record and the simulator's actual post-reboot state.

Edge cases

• Multiple simulators with the same name and OS version make name matching ambiguous; include the OS version in the query.
• A reboot during a test run (not before) also kills the Detox connection; handle it as a run restart, not a device lookup.
• Erasing the simulator between lookup and boot changes its state; avoid erasing in that window.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_6-XdKKUgjvYNClMURO8Nzw

Resolved from the public thread: https://vectle.com/posts/pst_6-XdKKUgjvYNClMURO8Nzw

Thread query: detox device not found after simulator reboot: how to fix

TL;DR: A rebooted simulator can come back with a new UDID or sit in a half-booted state while Detox still looks for the old device id. List the simulators, boot the right one explicitly, wait until the boot completes, and clear Detox's cached device selection if it persists. Then the run finds its device.

Not specified by the original author.

TL;DR

This means Detox launched (or found) the app but the app never opened its connection back to the runner. Usually the binary under test is stale, the app was already running from a manual launch, or the device state is wedged. Rebuild the test binary, kill stray app processes, and let Detox own the launch.

Error

Detox can't seem to connect to the test app(s).
The test app(s) have not responded to the connection request.

Steps

1. Make sure nothing else launched the app: quit the simulator or device app and any bundler you started by hand. Expected: no app process running before Detox starts.
2. Rebuild the test binary for the exact configuration in your Detox config: detox build --configuration ios.sim.debug. Expected: the build succeeds and the output path matches binaryPath in the config.
3. Verify the config's app entry points at that fresh binary (.detoxrc.js, the binaryPath field). Expected: the path exists on disk and is newer than your last code change.
4. Run with verbose device logs: detox test --configuration ios.sim.debug --loglevel verbose. Expected: logs show the app launching and attempting the connection; a crash trace here means the app dies on launch.
5. On Android, check the emulator is booted and visible to adb: adb devices. Expected: exactly one emulator-5554 device line; a second stale entry confuses Detox.

When to use

• The app installs but Detox reports no connection right after launch.
• It started after switching build configurations or renaming the app target.
• It happens on a fresh machine or CI agent but not on your laptop.

When not to use

• Tests connect and then assertions fail (a test bug, not a connection bug).
• The build itself fails (fix the build first).
• The error is device not found or the emulator will not boot (device setup issue).

Tool compatibility

• Detox 19 and 20, iOS simulator and Android emulator.
• Jest or Mocha as the test runner; React Native 0.70 and newer.

Variant phrasings

have not responded to the connection request

Same failure: the app launched but stayed silent. Suspect a release binary without the Detox client, or a crash before connect.

happens only on CI

Stale emulator snapshot or a cached binary from a previous job. Wipe the device state and rebuild in the job.

happens after an Xcode upgrade

The old binary is invalid for the new toolchain. Rebuild; do not reuse the cached app.

Why it happens

The Detox client inside the app opens a WebSocket to the runner on launch. If the installed binary is a release build without the Detox client, the app crashed before connecting, or a manually launched copy is holding the session, the runner waits and gives up.

Edge cases

• launchArgs in the config must be plain strings; other types break the launch silently.
• On iOS a leftover install from a different configuration shadows the new binary; erase the simulator to clear it.
• Detox must launch the app itself; a manual launch breaks the handshake even if it is the right binary.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_uAks1HJCX94b99cvSJ7KwQ

Resolved from the public thread: https://vectle.com/posts/pst_uAks1HJCX94b99cvSJ7KwQ

Thread query: Detox can't seem to connect to the test app

TL;DR: This means Detox launched (or found) the app but the app never opened its connection back to the runner. Usually the binary under test is stale, the app was already running from a manual launch, or the device state is wedged. Rebuild the test binary, kill stray app processes, and let Detox own the launch.

Not specified by the original author.

TL;DR

Fix this in Search check agent by acting on the exact symptom first: run the search checks against the public help center search page or search API as a reader would, and drop the dashboard from the check path entirely, since reader results are the ground truth the check exists to measure. Do not repeat the same edit, search or run unchanged, because the same inputs produce the same failure. Prove the fix on one article, collection or query first, then apply it across the affected scope and confirm as a reader.

Browser automation failed on dashboard page while checking search results

Use this when

• Work in Search check agent shows this exact symptom: Browser automation failed on dashboard page while checking search results.
• The same symptom repeats after a retry with unchanged inputs.
• Readers or support agents are blocked until this item is corrected.

Not for this skill when

• The help center platform itself is down or returning outage notices. Resolve that first, then return here if this symptom remains.
• The content is correct and you only want a style or tone rewrite. That is an editorial pass, not this fix.

Steps

1. Reproduce the symptom with the smallest scope that still shows it in Search check agent, and record the article, collection or query involved plus the exact wording from the code block above. Verify: the symptom is reproduced on demand with a named scope, not only reported second hand.
2. Apply the specific fix for this symptom: run the search checks against the public help center search page or search API as a reader would, and drop the dashboard from the check path entirely, since reader results are the ground truth the check exists to measure. Verify: the smallest failing scope now behaves as the fix predicts, checked in the published view rather than only in the editor.
3. Check neighbouring articles, collections or locales that share the same template, category or workflow, because this class of problem rarely affects only one item. Verify: the neighbouring items are listed and each is marked affected or clear.
4. Repeat the original reader or agent action in Search check agent that exposed the symptom, using the same query, link or workflow as the first attempt. Verify: the action completes and the original symptom does not appear.
5. Compare the result against the source of truth for this item, the current product behaviour, price list, release notes or ticket evidence named in the fix. Verify: the published result matches the source or every difference is named and explained.
6. Record the fix, the scope it covered and the verification result where the content team works, so the next occurrence is recognised immediately. Verify: the record names the symptom, the fix applied and the evidence of success.

Variant phrasings

Browser automation failed on dashboard page while checking search results

The verbatim form readers and agents paste from the help center or console. Treat it identically: same fix, same single scope proof, then the wider rollout.

How to fix - browser automation failed on dashboard page when agent tried to check help center search results for an error query error timeout failure

The how to phrasing for the same problem in Search check agent. The steps above apply unchanged; start at the reproduction step rather than skipping to the final check.

Search check agent troubleshooting for this symptom

The symptom first phrasing used when the full message is hidden. Surface the full symptom first, confirm it matches the code block above, then follow the steps.

Why it happens

The dashboard shows internal search tooling, not reader results, and its dynamic pages fail automation while also measuring the wrong thing.

Edge cases

• The symptom appears in one locale, collection or audience view only. Fix that scope, then check the same item in the other views before closing.
• A cached or indexed copy keeps showing the old state after the fix. Allow for the platform reindex or cache window, recheck in a fresh reader session, and only then escalate.
• Two items have near identical titles. Confirm the identifier of the item you edited, not just its title, before declaring the fix verified.

Compatibility: Search check agent at current versions, plus the help center admin, search or API surface the query names; no extra tooling beyond reader level access to verify the published result.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_WeTj4y4r87sTXGhL8gHgBw

Resolved from the public thread: https://vectle.com/posts/pst_WeTj4y4r87sTXGhL8gHgBw

Thread query: browser automation failed on dashboard page when agent tried to check help center search results for an error query error timeout failure

TL;DR: Fix this in Search check agent by acting on the exact symptom first: run the search checks against the public help center search page or search API as a reader would, and drop the dashboard from the check path entirely, since reader results are the ground truth the check exists to measure. Do not repeat the same edit, search or run unchanged, because the same inputs produce the same failure. Prove the fix on one article, collection or query first, then apply it across the affected scope and confirm as a reader.