A DNR rule with lower priority is being applied before a DNR rule of higher priority on Safari. Specifically, a low-priority DNR block rule that matches a request is being applied before a high-priority DNR redirect rule that matches the same request, preventing the redirect from occurring. The only way to get the high-priority redirect rule to occur is to remove the DNR block rule. This does not occur on other browsers. I have already submitted a Feedback Assistant report about this bug: FB16535579 How to reproduce: Create/install a web extension on Safari with the declarativeNetRequest and declarativeNetRequestWithHostAccess permissions Open the Web Extension Background Content console and add a redirect rule with a high priority number. For example: await chrome.declarativeNetRequest.updateDynamicRules({addRules: [ {id: 5000, condition: {urlFilter: "||www.google-analytics.com*/ga.js", resourceTypes: ["script"], domainType: "thirdParty"}, priority: 80, action: {type: "redirect", redirect: {url: “http://www.apple.com/”}}} ]}) Add a block rule of lower priority for the same urlFilter: await chrome.declarativeNetRequest.updateDynamicRules({addRules: [ {id: 5001, condition: {urlFilter: "||www.google-analytics.com^", domainType: "thirdParty"}, priority: 1, action: {type: "block"}} ]}) Visit https://efforg.github.io/privacybadger-test-fixtures/html/ga_surrogate.html Check the network tab and see that neither a request to Google Analytics nor apple.com appear. This means that the request to Google Analytics was blocked instead of being / before being redirected Remove the block rule: await chrome.declarativeNetRequest.updateDynamicRules({removeRuleIds: [5001]}) Reload https://efforg.github.io/privacybadger-test-fixtures/html/ga_surrogate.html. Check the network tab and confirm that there is a request to apple.com, showing that the redirect rule is only applied if the lower-priority block rule is removed. The priority of the DNR rules should handle this without having to remove a DNR rule. I have confirmed that the incorrect application of DNR rule priority happens on other top level domains, with other urlFilters, and with other redirect URLs. I confirmed that this is happening while I’ve granted my extension permissions on all websites.

DNR rules redirecting to an extension path lead to an error page: “Safari can’t open the page. The error is: “The operation couldn’t be completed. (NSURLErrorDomain error -1008.)” (NSURLErrorDomain:-1,008).” Here is a demo extension that replicates the bug: https://github.com/lenacohen/Safari-Test-Extensions/tree/main/dnr-extension-path-redirect This is an example of a redirect rule that leads to an error page instead of the extension path page: chrome.declarativeNetRequest.updateDynamicRules({addRules: [ { id: 2, priority: 1, action: { type: "redirect", redirect: { extensionPath: "/web_accessible_resources/test_redirect.html" } }, condition: { urlFilter: "||washingtonpost.com^", resourceTypes: [ "main_frame" ] } } ]}); The extension path is included in web_accessible_resources in the extension manifest: "web_accessible_resources": [{ "resources": [ "web_accessible_resources/test_redirect.html" ], I also submitted a bug report on Apple's Feedback Assistant: FB16607632