I’m a developer working on a Safari Web Extension that’s distributed via the App Store and also tested locally through Xcode. I’m running into an issue that’s affecting my ability to debug errors reported to my Sentry error logging instance from production.
The Problem
When an error is thrown in one of my extension scripts (e.g., background.js, popup.js, or content.js), the error is sent to Sentry but the captured JavaScript error stack trace replaces the file paths with the webkit-masked-url://hidden placeholder like this:
ReferenceError: Cannot access uninitialized variable.
at ? (webkit-masked-url://hidden/:14677:28)
at ? (webkit-masked-url://hidden/:16307:3)
This happens consistently across both App Store builds and local Xcode runs. It prevents me from seeing which script the error came from or resolving the actual source code lines using uploaded source maps in Sentry.
My Setup
Safari Version: 18.5 (Stable on macOS)
Distribution: App Store and local Xcode development
Extension Type: Safari Web Extension
Error Reporting: Sentry (@sentry/browser SDK)
Bundler: Webpack with inline-source-map
What I’ve Confirmed
I can see the actual source files in Safari’s Web Inspector under the Sources tab when the extension is running.
My source maps are uploaded to Sentry correctly and are associated with the matching release.
Errors from Safari are being captured by Sentry, but the file URLs are masked, so stack traces cannot be resolved against my original source.
My Question
Is this behavior (masking file URLs in stack traces with webkit-masked-url://hidden/) intentional for Safari Web Extensions?
If so, is there any supported method or workaround to allow exception stack traces to reveal the original script path (e.g., popup.js, background.js) so tools like Sentry or even console logs can point to real locations? I fully understand the privacy/security rationale behind the masking, but as the extension developer, this is making it extremely difficult to debug runtime issues in production.
I’d really appreciate any insight into:
Whether this masking is expected and permanent behavior
If there are any entitlements, debug settings, or Info.plist keys that can alter this behavior for development or for trusted/own extensions
If Apple recommends a different way to log extension errors that includes script name or source references
Thanks in advance for your help! I’m happy to share more technical details or try out suggestions.
Safari Extensions
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If the extension uses manifest v3 and a background script in the form of a service worker, then in Safari it is not possible to open the background script debugging window. If I expand the Developer menu in Safari, there is nothing under Web Extension Background Data (or disappear after click), which is an error. In other browsers (Edge, Chrome, Opera, Firefox) this works correctly.
If I switch the background script back to non-persistent script mode, everything works fine and from the Developer menu and the Web Extension Background Data submenu I am able to open the background script debugging window for the extension. Am I doing something wrong?
I develop a tab manager extension: https://apps.apple.com/ua/app/tab-finder-for-safari/id6741719894
It's written purely in Swift. All Safari interactions are done solely inside a SFSafariExtensionHandler .
But now i'm considering adding some features from Google Chrome's Extension API like window switching.
Is it possible to add a background.js worker to my existing Safari App Extension to have access to the beginRequest method override inside SFSafariExtensionHandler?
Without converting my extension from Safari App Extension to Safari Web Extenion?
I want to migrate from a Safari App Extension to a Safari Web Extension, but don't know how to get rid of the message, telling users that my extension can access their passwords. Here is a message which I see:
I was thinking that this might be because all Safari Web Extension get this type of access, but I have a Safari Web Extension which does not require such level of access:
Here is the manifest:
{
"manifest_version": 2,
"default_locale": "en",
"name": "__MSG_extension_name__",
"description": "__MSG_extension_description__",
"version": "1.1",
"icons": {
"48": "images/icon-48.png"
},
"background": {
"scripts": [
"background.js"
],
"persistent": true
},
"browser_action": {
"default_popup": "popup.html",
"default_icon": {
"16": "images/toolbar-icon-16.png"
}
},
"permissions": [
"nativeMessaging", "tabs"
]
}
and here is the Info.plist file:
Here is the entire code of the extension:
https://github.com/kopyl/web-extension-simplified
It seems Safari 18's fetch() does not include credentials even credentials: include and safari extension has host_permissions for that domain.
Is there anyone has this problem?
I try to request in popup.js like this:
const response = await fetch(
url,
{
method: 'GET',
mode: 'cors',
credentials: 'include',
referrerPolicy: 'no-referrer',
}
);
and it does not include the cookie from host_permissions.
Those code worked in Safari 17 (macOS Sonoma).
Hi, after upgrading MacOS (MB Air M1 Version 26.2 (25C56)) & Safari (Version 26.2 (21623.1.14.11.9)) to latest versions, we are experiencing a new bug occurring with our web extension (Click & Read) on local storage writing and getting this error :
Invalid call to browser.storage.local.set(). Disk I/O error.
This doesn't happen on other browsers (chromium, Firefox).
export const setLocalStorage = async (value: object) => {
try {
await browser.storage.local.set(value);
} catch (error) {
console.error("[Click & Read] Error setting local storage", error);
}
};
I'm building a macOS extension that needs to track multi-step navigation chains (A → B → C) to adjust behavior based on where users came from.
Current approach: Using webNavigation.onBeforeNavigate to detect intermediate steps, but experiencing issues in Safari that don't occur on Chrome/Firefox/Edge.
Questions:
Is webNavigation the right API for tracking redirect chains in Safari?
Does ITP/Private Browsing affect event delivery?
Any alternative approaches recommended?
(Safari version 26.0.1)
Any guidance appreciated!
I am trying to run JavaScript only after the page has loaded, and according to here - https://developer.apple.com/documentation/safariservices/safari_app_extensions/injecting_a_script_into_a_webpage, I should use DOMContentLoaded. However, it does not seem to work.
This is my content.js file:
function runOnStart() {
document.addEventListener('DOMContentLoaded', function(e) {
document.body.style.background = "rgb(20, 20, 20)";
document.html.style.background = "rgb(20, 20, 20)";
var divElements = document.body.getElementsByTagName('div');
for(var i = 0; i < divElements.length; i++) {
let elem = divElements[i];
elem.style.background = "rgba(255, 255, 255, 0.05)";
}
});
}
runOnStart();
If I take the code outside of the event listener, it runs fine, but a lot of the elements haven't loaded in yet so it doesn't work as it should.
The function is definitely running, but the event listener simply doesn't work. I appreciate any help you can give!
I'm trying to sync authentication data from my iOS app to a Safari Web Extension using App Groups, but the extension isn't consistently receiving the data.
Setup:
App Group: group.com.airaai.AiraApp (configured in both app and extension)
iOS app writes auth data using UserDefaults(suiteName: "group.com.airaai.AiraApp")
Extension's Swift SafariWebExtensionHandler reads from App Groups in beginRequest()
Extension's JavaScript reads from browser.storage.local
Problem:
Extension popup always shows "logged out" even when:
User is logged into main iOS app
Auth data exists in App Groups (verified via native module logs)
Handler successfully writes test values to extension storage
Current Behavior:
Handler CAN read from App Groups ✅
Handler CAN write test values to extension storage ✅
But auth data doesn't appear in browser.storage.local when popup checks ❌
Popup reads empty keys even though handler logged writing them
Code:
// Handler reads from App Groups
guard let sharedDefaults = UserDefaults(suiteName: "groupName") else { return }
let authData = sharedDefaults.string(forKey: "auth_data")
// Handler writes to extension storage (tried multiple suite names)
let extensionDefaults = UserDefaults(suiteName: Bundle.main.bundleIdentifier ?? "")
extensionDefaults?.set(authData, forKey: "oauth_token")
extensionDefaults?.synchronize()
// Popup reads from storage
browser.storage.local.get(['oauth_token']).then(data => {
console.log(data); // Always empty {}
});
What I've tried:
✅ App Groups properly configured in both targets
✅ Extension has App Groups capability enabled
✅ Multiple UserDefaults suite names (bundle ID, bundle ID + suffix)
✅ Delayed sync attempts in handler
✅ Comprehensive logging
Questions:
What is the correct UserDefaults suite name for Safari extension storage on iOS?
When does beginRequest() get called? Can it be triggered manually?
Is App Groups the right approach, or should I use a different pattern?
Alternatives I've considered:
Deep link/redirect method (app opens Safari with token in URL)
Content script intercepts URL and sends to background script
Is this a supported approach for iOS Safari extensions?
Any guidance or examples would be greatly appreciated!
I’m developing a Safari App Extension and I want to debug the background.js script.
However, I can’t find any tool or option to do this.
When I run the extension from Xcode using the ProjectName Extension (macOS) scheme, I expect to see a “ProjectName” item under the Develop → Web Extension Background Content menu.
But there’s nothing there.
Has anyone encountered the same issue? How did you fix it?
Environment:
Manifest Version: V3
Safari: 26.0.1 (21622.1.22.11.15)
Xcode: 26.0.1 (17A400)
Could somebody provide hello world example of Safari Extension which is able to call on-device Foundation Model (Apple Intelligence)?
I cannot find any examples yet
I’m observing an intermittent issue with a Safari Web Extension on macOS 15.7 (Safari 26.0.1). After installing the Safari extension from the App Store, it appears under Settings → Extensions, but the enable checkbox is often missing.
Sometimes, after restarting Safari multiple times, the checkbox becomes visible. However, even when I manage to enable the extension, reopening Safari often hides the checkbox again.
However, I don't see this issue in safari 26 with macOS 26
I’d like to know if this behavior is a known issue with Safari 26 or macOS 15.7?
Any workaround available?
After updating to Safari 26.0 (on macOS Sequoia or Tahoe), the Declarative Net Request (DNR) API rule with "type": "redirect" no longer works as expected.
When the rule is applied, the browser initially shows a banner at the top of the page:
"This webpage was reloaded because a problem occurred."
After the reload, the page fails to load and displays an error page with the message:
"A problem repeatedly occurred with https://extensionworkshop.com/?test=true "
This behavior is new in Safari 26.0. The same rule was working correctly in earlier Safari versions (17.x / 18.x).
our company created a web safari extension.
before iOS 26 (beta) release we would archive our extension and install to our devices no problem.
since iOS 26 (beta) (we also tried in beta 4 23A5297m) the extension would archive perfectly but when installing the extension would just not run. its found in settings under safari extension, but when enabled the extension and open safari it will show error message "Ext" is no longer available.
to rule out all code issues, we built a new project from scratch with a new bundle id, tried to archive with no problem, but when installed in an iphone 16 with iOS 26 BETA (23A5297m) same error ocurs it installs but when opening safari it will give an error message saying extension is no longer available.
attached in the google drive link is a zip file of the new project, a zip file with a succesfull build of the ipa file with enterprise distribute, a video of the entire proccess and the error that the iphone gives.
also attached a log file from the iphone that includes the install and the crash of the app.
within the logs there is a log saying Error occurred during transaction: The provided identifier "dev.sacal.ext" is invalid.
before ios 26 the exact steps worked perfectly.
https://drive.google.com/file/d/1PYDOv8IRvRY_ouqiOc0sJdcfh0CHbL72/view?usp=sharing
I'm developing a web extension for Safari on iOS using MV3.
The extension is working fine in Chrome, but in Safari I experience some seemingly random issues. I would like to debug it, but here is my problem.
I have my iPhone connected via cable to Mac, and it works fine with XCode, so I assume this part is OK.
I open Safari or Safari Tech Preview (doesn't matter) on my Mac, developers options are enabled, and in the Develop menu, under my iPhone section, there are things I can debug. There is an entry "[Ext name] - Extension Service Worker" but when I click it, it's empty. Web inspector pops up, but there are no network requests, no logs, nothing. I know the extension is working, because I can stream log to my HTTP server, but I don't see them here at all. I can use console to trigger commands like chrome.storage.local.get(null, console.log) and it shows my local store, so why I don't see any logs? Also, the background script is not visible in the Sources tab, just one weird request:
navigator.serviceWorker.register('safari-web-extension://E3449EA7-EC25-4696-8E6C-[ID HERE]/background.js');
</script>
Any ideas what went wrong? The entire team of 4 people has the same issue and we can't move forward because of that.
Also, the Develop => Service workers or any other menu section doesn't show my service worker. Logs for websites running on my phone are visible and in general web inspector for them works fine.
I have observed Safari App starts crashing when running with my safari extension.
Our Safari extension polls the host app every 60s. The extension receives and completes requests in
func beginRequest(with context: NSExtensionContext)
(we always call context.completeRequest(...)). The crash is intermittent: beginRequest itself does not throw.
Looking for guidance about likely causes. I am attaching the snippet from crash report.
Crashed Thread: 0 Dispatch queue: com.apple.main-thread
Exception Type: EXC_CRASH (SIGKILL)
Exception Codes: 0x0000000000000000, 0x0000000000000000
Termination Reason: Namespace RUNNINGBOARD, Code 3490524077
Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0 libsystem_kernel.dylib 0x1856f5c34 mach_msg2_trap + 8
1 libsystem_kernel.dylib 0x1857083a0 mach_msg2_internal + 76
2 libsystem_kernel.dylib 0x1856fe764 mach_msg_overwrite + 484
3 libsystem_kernel.dylib 0x1856f5fa8 mach_msg + 24
4 CoreFoundation 0x185822cbc __CFRunLoopServiceMachPort + 160
5 CoreFoundation 0x1858215d8 __CFRunLoopRun + 1208
6 CoreFoundation 0x185820a98 CFRunLoopRunSpecific + 572
7 HIToolbox 0x1912c327c RunCurrentEventLoopInMode + 324
8 HIToolbox 0x1912c64e8 ReceiveNextEventCommon + 676
9 HIToolbox 0x191451484 _BlockUntilNextEventMatchingListInModeWithFilter + 76
10 AppKit 0x189745a34 _DPSNextEvent + 684
11 AppKit 0x18a0e4940 -[NSApplication(NSEventRouting) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 688
12 Safari 0x1b801cce4 -[BrowserApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 228
13 AppKit 0x189738be4 -[NSApplication run] + 480
14 AppKit 0x18970f2dc NSApplicationMain + 880
15 Safari 0x1b83dd0b0 SafariMain + 468
16 dyld 0x185396b98 start + 6076
Since probably the late iOS 17.4.x, 17.5.1 and still now in 17.6 beta our extension has been experiencing issues with the accompanying background script or service worker being permanently killed with no warning after about 30-45 seconds after initial installation (installation, not page load!).
In all other browsers (including Safari on MacOS) unloading the service worker is part of the normal lifecycle to save memory and CPU if it is idle. In our extension the service worker is used only during the first 5-10 seconds of every page visit, so we are used to seeing it unload after that and consider this a good thing. However, normally, the service worker is able to wake back up when needed - which is no longer the case in iOS.
Once dead, nothing a normal user would do can wake the service worker back up:
No events like webNavigation or similar will trigger anymore
Any attempt to call sendMessage to it from a content-script also does not wake up the service worker and instead returns undefined to the content script immediately
Closing and opening Safari does not start it again
The only two things that will give the service worker another 30-40 seconds of life is a reboot of the device or disabling and then re-enabling the extension. During those few second the extension is working perfectly.
There are no errors or indications in the logs of what is going on and the extension works just fine in Chrome, Firefox, Edge as well as Safari on MacOS and Safari in the Mobile simulator. Only actual iOS devices fail.
It seems like a temporary workaround is to change the manifest to not load the service worker as a service worker by changing
"background": {
"service_worker": "service.js"
}
to
"background": {
"scripts": ["service.js"],
"persistent": false
}
With this change (courtesy of https://forums.developer.apple.com/forums/thread/721222) the service worker is still unloaded but correctly starts up again when needed. Having to make this change does not seem to be consistent with manifest v3 specs though (see this part in Chrome’s migration guide as an example: https://developer.chrome.com/docs/extensions/develop/migrate/to-service-workers#update-bg-field).
According to the release notes of 17.6 beta this bug was supposedly fixed:
“Fixed an issue where Safari Web Extension background pages would stop responding after about 30 seconds. (127681420)”
However, this bug is not fixed - or at least not entirely fixed. It seems to work better for super simple tests doing nothing but pinging the service worker from the content script, but for the full blown extension there is no difference at all between 17.5.1 and 17.6.
Has there been a change in policy about service workers and background scripts for Safari in iOS?
Are anyone else seeing this issue?
Also seemingly related:
https://forums.developer.apple.com/forums/thread/756309
https://forums.developer.apple.com/forums/thread/750330
https://developer.apple.com/forums/thread/757926
https://forums.developer.apple.com/forums/thread/735307
I'm experiencing a Safari Web Extension issue where the non-persistant background script seems to crash after 30 seconds even when the content script is messaging it.
Here is a minimal-reproducible example. When running in an emulator, the background script will stay responsive forever. However, when running on a physical device, the background script becomes non-responsive after 30 seconds of activity. It never becomes responsive again until I toggle the extensions enable/disable toggle, after which it stays active for 30 seconds and then crashes again.
Hi everyone,
I’m encountering a serious reliability issue with message passing in my Safari extension on iOS 18.4.1 and iOS 18.5
In my extension, I use the standard messaging API where the background script sends a message to the content scrip. The content script is listening using:
browser.runtime.onMessage.addListener(handler);
This setup has been working reliably in previous versions of iOS, but since updating to iOS 18.4.1 and iOS 18.5, I’ve noticed that messages sent from the background script are not consistently received by the content script. From my logs, I can confirm that:
The background script is sending the message.
The content script’s listener is not always triggered.
There are no errors or exceptions logged in either script.
It seems as if browser.runtime.onMessage.addListener is either not getting registered in time or failing silently in some instances.
This issue is intermittent and does not occur all the time.
Has anyone else experienced similar issues in iOS 18.4.1 and 18.5? Are there any known changes or workarounds for ensuring reliable communication between background and content scripts in this version?
Any help or insights would be greatly appreciated.
Thanks!
Safari Web Extension for enterprice distribution:
If I press run button on xcode it shows the safari web extension toggle and works perfect
When installed through exported ipa, the web extension toggle dissapears, it doesnt matter how it was installed through mdm, link, or directly ipa from xcode
I just exported an ipa as debugging and it worked when I pushed the ipa