NOOP Not Working? Fixes for Every Common Problem (2026)

Most NOOP problems have one of four causes: an install warning (Play Protect on Android, Developer Mode on iPhone, Gatekeeper on Mac), the WHOOP app still holding the strap's Bluetooth link, Android closing NOOP in the background, or Charge still learning your baseline. Check the quick fixes first, then find your exact problem in the tables below.

Try these first

These fix most problems in a minute:

Update NOOP to the latest version from the download page.
Fully close the official WHOOP app on your phone, or turn that phone's Bluetooth off.
Charge the strap and wear it snug, sensor against your skin, within a metre of your device.
Turn Bluetooth off and on on the device running NOOP.
Check NOOP's permissions: Bluetooth (and Nearby devices on Android) must be allowed.
Restart NOOP, and if that doesn't help, restart the device.

Installing NOOP

Android

Problem	Fix
"For your security, your phone isn't allowed to install unknown apps"	Tap Settings and turn on Allow from this source. Step by step
Play Protect blocks it, with no Install anyway	Three ways past Play Protect, plus Samsung's Auto Blocker
There was a problem parsing the package	The download didn't finish, or your Android is older than 8.0. Download again.
App not installed	Free up space, or remove an older NOOP signed by someone else. Details
The Install button doesn't respond	Turn off screen overlays (blue-light filters, chat bubbles) and try again.

iPhone

Problem	Fix
"Given data not valid JSON" when adding the source	Use the exact `raw.githubusercontent.com` source URL. Copy it here
"AltServer could not sign in" / `NSCocoaErrorDomain 3840`	A known AltStore bug on 26.2. Use SideStore instead
Untrusted Developer	Trust your Apple ID in VPN & Device Management
"Developer Mode required"	Turn on Developer Mode and restart
"Maximum number of apps"	A free Apple ID allows 3 sideloaded apps, including SideStore or AltStore. Remove one.
NOOP stopped opening after a week	Refresh it in My Apps

Mac

Problem	Fix
"NOOP" Not Opened or "NOOP" is damaged	Open Anyway, or one Terminal command
No Open Anyway button	Try opening NOOP first; the button appears for about an hour afterwards.
`brew install` can't find NOOP	There's no Homebrew cask right now. Download it directly.

Pairing and connection

Problem	Fix
The strap isn't in Bluetooth settings	Normal. Pair it from inside NOOP, never from Settings.
NOOP can't find the strap	Close the WHOOP app, charge and wear the strap, keep it close, check permissions. Pairing guide
"Bond refused" or "Encryption is insufficient" (5.0 / MG)	The strap is still bonded elsewhere. Free it and use pairing mode
Heart rate works, but buzz, alarm, double-tap or history don't	The strap isn't fully bonded to this device; heart rate uses a separate signal. Disconnect it everywhere else and pair again.
Live HR · not fully paired	Same as above: something else still holds the strap.
It keeps disconnecting	Keep the strap within range, and on Android let NOOP run in the background.
Paired to a phone and a Mac at once, and things act oddly	A strap bonds with one device at a time. Choose one.

Syncing and missing data

Problem	Fix
Whole nights missing (Android)	Android closed NOOP overnight. Allow background running.
Data stops after I leave the house	The strap stores data and sends it when it's back in range. Keep it near your device for a few minutes.
No steps on a WHOOP 4.0	NOOP can't read steps from a 4.0 yet. Import steps from Apple Health or Health Connect. How
Sleep or recovery missing on a 5.0 / MG	Expected for now: only live heart rate is fully supported on these straps. Import your WHOOP export for history.
My old WHOOP history isn't there	NOOP starts fresh. Import your WHOOP export.
Data gone after reinstalling	NOOP keeps no cloud copy. Restore a backup if you made one.

Scores and numbers

Problem	Fix
Charge says Calibrating	It needs at least four nights to learn your HRV. Don't tap Recalibrate. Why
Effort shows No Data	It needs at least 10 minutes of heart rate for the day. Wear the strap and let it sync.
Resting heart rate is lower than in WHOOP	Expected: NOOP uses your night's lowest steady level. Explained
HRV is very different from WHOOP	Small gaps are normal. If it's about double, report it with your strap log.
A score looks wrong for one day	Check the strap was worn snug that night; loose wear gives patchy data.

Updates and backups

Problem	Fix
Android: "App not installed" when updating	The installed copy was signed by someone else. Back up, uninstall it, then install the official APK.
iPhone: the update isn't showing	In SideStore or AltStore, pull down on My Apps to refresh.
Mac: blocked again after updating	Repeat Open Anyway or the Terminal command.
Restored a backup but nothing changed	On iPhone and Mac, quit and reopen NOOP after importing a backup.

Still stuck? Report it

NOOP runs entirely on your device, so its developers need a strap log to tell a real fault from a setup detail.

Save your strap log
On Android: Settings → Strap → Share strap log (for bug reports). On iPhone and Mac: open Settings and use the Strap log section to copy or save it. The log contains no heart-rate or other health values.
Note your setup
Your NOOP version (in Settings → About), your device and its system version, and your strap model (4.0, 5.0 or MG).
Post it in the right place
Bugs: an issue on NOOP's GitHub. Setup questions: r/NoopBand or NOOP's Discord. A mistake in one of our guides: tell us.

Frequently asked questions

Why won't NOOP find my WHOOP strap?

Usually because the official WHOOP app is still holding the strap's Bluetooth link. Fully close the WHOOP app (or turn off that phone's Bluetooth), wear the strap close to your device, and scan again in NOOP. A WHOOP 5.0 or MG also needs pairing mode: tap it until its lights flash blue.

Why does my WHOOP strap not show in Bluetooth settings?

That's normal. WHOOP straps don't use a profile that phones and Macs list in their Bluetooth settings. Only apps like NOOP can see them, so pair from inside NOOP.

Why does NOOP miss nights on Android?

Android is closing NOOP in the background to save battery. Allow NOOP to run in the background: when Android asks Stop optimising battery usage?, tap Allow, or set NOOP's battery usage to Unrestricted in Settings.

Why did NOOP stop opening on my iPhone?

Apps signed with a free Apple ID last 7 days. SideStore or AltStore normally renews them in the background; if that didn't happen, open it and tap Refresh All in My Apps. Your data is kept.

Why does my Mac say NOOP is damaged?

It isn't. NOOP isn't notarized by Apple, so macOS flags the download. Run xattr -dr com.apple.quarantine /Applications/NOOP.app in Terminal, or use Open Anyway in System Settings → Privacy & Security.

Where do I report a bug in NOOP?

Open an issue on NOOP's GitHub with your NOOP version, device and strap model, and attach your strap log. This site writes guides but doesn't develop the app.

NOOP not working? Fixes for every common problem