My Mac app and its Safari web extension share an app group, and I want to notify the web extension native process when the app makes a change to the app group NSUserDefaults, but I can't find a good way to do this. According to the documentation, "You can use key-value observing to register observers for specific keys of interest in order to be notified of all updates, regardless of whether changes are made within or outside the current process." In my testing, however, this doesn't work in the web extension process. I'm using NSUserDefaults addObserver forKeyPath, but observeValueForKeyPath never gets called. I've also tried NSDistributedNotificationCenter, but the web extension process doesn't receive the notifications sent by the main app. Are either of these supposed to work? If not, are there any alternatives?

When a DNR rule is set for a specific URL and the request receives a server-side redirect (e.g., 302) to a different URL that does not match the urlFilter, the rule still seems to apply to the redirected request. We are using macOS 15.4 and Safari 18.4. For example, consider two sequential calls: call1 and call2. call1 triggers a 302 redirect to call2. A DNR rule is created to add a "Cookie" header to call1 based on its URL. Unexpectedly, the same cookie is also added to call2, even though call2's URL does not match the rule's urlFilter. This results in the Set-Cookie response from call1 being ignored, and call2 receiving the manually set cookie instead—leading to incorrect behavior. This issue doesn't occur in Chrome or Firefox, where the rule is not applied to the redirected request if the URL no longer matches. We are looking for assistance in fixing these issues and having our Safari Extension function the same as it does in Firefox and Chrome.

We’re encountering an issue when trying to add non-standard headers to outgoing requests using Declarative Net Request (DNR) rules in our Safari Web Extension. Tested on macOS 15.4 with Safari 18.4. Specifically, when attempting to add a custom header such as "X-Custom-Header" using a DNR rule, the header does not appear in the request. We are able to add standard headers like "Authorization" and "Cookie" to the request successfully using the same method. This behavior suggests that Safari may be filtering or blocking non-standard headers when set via DNR rules, unlike other browsers. In Chrome and Firefox, the same rule adds the "X-Custom-Header" header without any issue. We are looking for assistance in fixing these issues and having our Safari Extension function the same as it does in Firefox and Chrome.

We’re seeing an issue in our Safari Web Extension where not all cookies from the Set-Cookie response header are accessible. We are using macOS 15.4 and Safari 18.4. In the webRequest.onHeadersReceived callback, the Set-Cookie header returned by Safari only includes some of the cookies set by the server. If multiple Set-Cookie headers are present, we seem to receive only a partial list, some cookies are missing entirely. In Chrome and Firefox, the same callback provides all cookies set by the server without issue. We are looking for assistance in fixing these issues and having our Safari Extension function the same as it does in Firefox and Chrome.

Safari Extension Error: “Non-persistent background content cannot listen to webRequest events.” after macOS 15.4 / Safari 18.4 Update We’re seeing the following error in the Safari Extensions tab after updating to macOS 15.4 and Safari 18.4: “Non-persistent background content cannot listen to webRequest events.” This error did not appear prior to the update, and we haven’t found any official documentation stating that webRequest API is no longer supported in Safari. In our extension (Manifest V3), we are using the webRequest.onHeadersReceived callback to intercept response headers and read updated cookies. While the functionality itself still works as expected. we’re able to access the response headers and this error is now shown in the Extension settings page. We are not seeing this issue in other browsers (Chrome, Firefox) using the same Manifest V3 setup. Is there any plan to deprecate webRequest support in Manifest V3 for Safari? We’d appreciate any clarification or guidance on how to handle this going forward.

Hello, According to the documentation: If you provide your extension in macOS and don’t want to use the Mac App Store for distribution, you can sign and notarize your extension’s app with a Developer ID to distribute it outside the Mac App Store. However, I found this to be untrue in practice. Even after signing and notarising the Safari extension correctly, it is not possible to enable it in Safari without turning on "allow unsigned extension". This makes it impossible to distribute your Developer ID–signed and notarized extension outside the Mac App Store. I would like to distribute my web extension directly to employees in my organization using MDM without having each user manually enable "allow unsigned extension" for it to work. Any way to make it work? The documentation is quite confusing in this aspect, it says "Safari only supports signed extensions" but my extension is rejected even if notarised and signed.

updateDynamic rules is blocking ads on my device with iOS 17.4, but on my iOS 18 device the same code is not blocking ads. Is this a known issue?

Hello - we have a Mac application that uses a browser extension and the web extension JS APIs to communicate with Safari. During user testing we found that the tab title and tab URL properties are empty when obtaining the set of open windows via windows.get() after a Safari restart. We are testing with Safari 18.4 (20621.1.15.11.10). We have made a TestFlight version of our app and extension available to help with testing: https://testflight.apple.com/join/Va8Zdv9d. Screenshot and screen recording are attached to the Feedback ID supplied below. STEPS TO REPRODUCE Install Tabby via the TestFlight link Enable the Tabby for Safari extension in the Safari extensions dialog Grant permissions for Tabby for Safari to all windows all the time Within Safari, open two windows each with at least two tabs Within the Tabby app, ensure you see the windows and tabs listed correctly (tab title displayed for each) Quit and restart Safari Expected behavior Safari re-opens existing windows and Tabby displays title for each tab Observed Safari re-opens existing windows but within Tabby all tabs except the current tab are displayed with a title of “Start Page”. Under the hood the tab title and tab URL properties are empty when returned via a windows.get() call after Safari restarts. NAME AND APPLE ID OF APP Tabby - Browser Tab Manager 1586203406 FEEDBACK ASSISTANT ID FB16389506

When our Safari Web Extension makes a api request from its background script (registered via "scripts" in manifest.json, e.g., "background": { "scripts": ["js/background.bundle.js"] }) to our authenticated API endpoint (https://api-domain/user), the Cookie header is not included in the request. This occurs only when the extension is running within a non-default Safari User Profile. This causes our API to treat the user as unauthenticated. The exact same extension code, manifest, and API call work correctly (Cookie header is present and user is authenticated) when the extension is running in the Default Safari User Profile.

We have an existing Safari App Extension distributed outside the App Store (self-distributed). Recently, we converted another browser extension to a Safari Web Extension and used the same bundle ID as the original application to avoid any change on the CX side. After distributing this updated app, we noticed that the Safari extension was disabled on users' machines, and users are now required to manually re-enable it in Safari's preferences. Is this the expected behavior and is there way to avoid this for future updates ?

I have an app which has at least two extensions: A Content Blocker extension with a request handler that returns an appropriate NSExtensionItem as part of beginRequest. A different file URL is returned depending upon if the content blocking is on or off by a user setting A Safari Web Extension that includes a toolbar button and popover that enables users to enable or disable the ad blocking of the content blocker extension All three targets (App, Content Blocker appex and Web Extension appex) use an App Group default to read and set the on or off status of the content blocking. When the user changes the content blocking status, the app group default is updated and SFContentBlockerManager.reloadContentBlocker(...) is called. The Content Blocker extension reads the default and then returns the appropriate file URL. The issue is, I have noticed that whenever SFContentBlockerManager.reloadContentBlocker(...) is called from the app, Safari always applies the correct rules from the returned file URL. However sometimes when SFContentBlockerManager.reloadContentBlocker(...) is called from the Safari Web Extension using native messaging, Safari does NOT apply the correct rules from the returned file URL. Using logging I have confirmed that the Content Blocker extension always returns the appropriate file URL irrespective if called as a result of the app or the web extension. Despite this, Safari does not seem to always apply the returned file URL rules when it is called from the Safari Web Extension appex. In these cases, quitting Safari and relaunching it seems to make it apply the rules correctly (obviously this is applying it due to its launch state, not due to the Web extension appex asking it to do so at that point). All targets have access to the App Group location where the active content blocking file URL belongs and the inactive content blocking file URL is within the Safari content blocker target as a resource. I don't think this is a memory status issue as I cannot see the Content Blocker extension being killed when it returns complex rules --- the fact it always works when called via the app also seems to rule this possibility out. This brings up a number of questions: Is calling SFContentBlockerManager.reloadContentBlocker(...) from a different appex, of the same app target and app group supported? (it seems to work sometimes and did work in previous versions of the app). Is there an issue that the Content Blocker extension sometimes returns a file URL that perhaps the calling Web Extension appex may not have access to (even though Safari should via the Content Blocker extension)? Any other ideas of why this may not be working correctly? Has anyone else experienced this? It seems to happen on both iOS and macOS Safari using the same codebase.

Hi! I'm working on a web extension for Safari and I need to send messages from the containing application to JavaScript. For this I use the method class func dispatchMessage( withName messageName: String, toExtensionWithIdentifier identifier: String, userInfo: [String : Any]? = nil ) async throws of the SFSafariApplication class. If the site is opened in Safari in normal mode, everything works as expected. However, if the site is "docked", the messages are not transmitted to this "Web App". Is it possible to somehow link the container application to the docked website so that messages from the application are received by this "Web App"? That you.

Hello - we have a Mac application that uses a browser extension and the web extension JS APIs to communicate with Safari. As of macOS 15.4 / Safari 18.4 the tab OnAttached and tab onDetached events are no longer received. After some testing we verified that the events were working properly as of macOS 15.3 / Safari 18.3 but appear to have been broken in macOS 15.4. Note a similar issue was reported previously for Safari 17.6 and was fixed in macOS 15.0 (FB14324177). We have made a TestFlight version of our app (Tabby) available to simplify debugging via https://testflight.apple.com/join/Va8Zdv9d. To reproduce the issue: Install the Tabby TestFlight build on macOS 15.4 or 15.4.1 Open Safari, go to Safari settings and select the Extensions tab Enable the Tabby extension and grant permissions to all windows all the time Open a Safari window with at least 3 tabs Note the open window and tabs displayed in Tabby In Safari, perform a tab detach by dragging a tab out of the window Expected behavior Within Safari the detached tab should now be in it’s own window, and via the onDetached event Tabby should update to show the tab in it’s own window AND removed from the original window. Observed Safari fails to send the onDetached event and Tabby will continue to display the detached tab in its original window in addition to the new window. You can also use the repro steps above to observe the onDetached event being received or not by Tabby in the Safari developer console. The same steps but re-attaching the tab to the original window can be used to observe the onAttached event being received or not. We’ve attached two screen recordings to the Feedback ID below, one showing the events working on macOS 15.3, and one showing the events failing to be received on macOS 15.4.1. Note it also fails on macOS 15.4. FEEDBACK ID: FB17367977

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!

I've been unable to successfully get a webpage to send a message to a Safari web extension, no matter what I try doing. I've added the following to my manifest.json file, and it's running manifest v3 { "externally_connectable": { "matches": [ "*://mywebsite.com/*", "*://localhost:3000/*" ] } } My web page executes the following code snippet. I've tried this both while running my site locally (on localhost) and pushed to production. let safariExtensionId = "co.companyname.productname.Extension (ABCD1234)" browser.runtime.sendMessage(safariExtensionId, { greeting: "hello"}, function(response) { console.log("Received response from background page"); console.log(response.farewell); } ); In the Safari web extension's background.js file, I've added the following onMessageExternal listener: browser.runtime.onMessageExternal.addListener((message, sender, sendResponse) => { console.log("Received message from the sender."); console.log(message.greeting); sendResponse({ farewell: "Goodbye!" }); }); This is directly copied from the instructions in this WWDC video: https://developer.apple.com/documentation/safariservices/messaging-between-a-webpage-and-your-safari-web-extension It's also extremely difficult to debug what's happening since the extensions service working frequently does not appear in the Web Extension Background Content menu Is there something I'm doing wrong, or a bug I'm not aware of?

Hi! I'm working on a web extension for Safari and I need to send messages from the containing application to JavaScript. For this I use the method class func dispatchMessage( withName messageName: String, toExtensionWithIdentifier identifier: String, userInfo: [String : Any]? = nil ) async throws of the SFSafariApplication class. If the site is opened in Safari in normal mode, everything works as expected. However, if the site is "docked", the messages are not transmitted to this "Web App".

Even default Safari Web Extension project is not displayed on iOS 18.4 simulator ("No extensions installed"), so it's not possible to test extensions in simulator, only on real device.

Hi, I’m working with the SFExtensionProfileKey in my Safari Web Extension. As I understand it, this key is to get the UUID of the profile currently in use. However, it seems to be missing (no key in userInfo) when the default profile is active. Also, I haven’t found any API to get a profile’s human-readable name or list all available profiles. Could someone clarify: If the value of SFExtensionProfileKey is absent, can I safely assume the default profile is in use? Is there a supported way to get a profile’s display name? Does Safari expose an API for getting all profiles? Thanks in advance for your insights!

Hi everyone, I’m encountering a critical reliability issue with message passing in my Safari Web Extension on iOS 18.4.1 and iOS 18.5. In my extension, I’m using the standard messaging API. The background script sends a message to the content script using browser.tabs.sendMessage(...), and the content script registers a listener via: browser.runtime.onMessage.addListener(handler); This setup has been working reliably in all prior versions of iOS. However, after updating to iOS 18.4.1 and 18.5, I’ve noticed the following behavior: ✅ The content script is successfully injected, and onMessage.addListener is registered (I see logging confirming this). ✅ The background script sends the message using the correct tabId (also confirmed via logs). ❌ The content script’s onMessage listener is not consistently triggered. ⚠️ This issue is intermittent, sometimes the message is received, sometimes it is silently dropped. ❌ No exceptions or errors are thrown in either script, the message appears to be sent, but not picked up from the content script message listener.

In a Safari Web Extension using Manifest V3, how can a content script access an HTML file that is bundled with the extension (e.g., to inject it as an iframe)? Safari's CSP seem to prevent the use of browser.runtime.getURL() in the MAIN world — is there a recommended way to load such resources securely?