Summary
Website pages often fail to load or display content when ad blockers are active primarily because these tools block scripts, network requests, or content elements that they mistakenly identify as ads or trackers. This can happen due to widely used filter lists targeting specific domains or code patterns, leading to legitimate website components being inadvertently blocked. Additionally, some websites employ anti-adblock technologies that actively prevent content display if an ad blocker is detected, compelling users to disable them for access.
Key findings
- Script and Request Blocking: Ad blockers, such as uBlock Origin, Brave Shields, or Firefox's Enhanced Tracking Protection, prevent websites from loading by blocking essential JavaScript files, like those from Marketo forms, and network requests to domains associated with ads or tracking.
- False Positives: A significant cause of content failure is when ad blockers' filter lists mistakenly identify legitimate website elements-including CSS classes, IDs, content-loading domains, or third-party scripts-as advertising material due to similar naming conventions or shared hostnames.
- Anti-Adblock Measures: Websites increasingly use anti-adblock scripts to detect ad blocker presence. Upon detection, these sites can intentionally prevent content from loading or display a message, effectively blocking access for users with ad blockers enabled.
Key considerations
- User Troubleshooting: Users experiencing page loading issues due to ad blockers can often resolve them by temporarily disabling their ad blocker or by seeking direct links to content, like PDFs, to bypass blocked forms or scripts.
- Website Design Impact: Developers should be aware that reliance on complex third-party scripts or certain content loading methods, if those resources share patterns or domains with ad elements, can inadvertently lead to content being blocked by ad blockers.
- Filter List Mechanics: Understanding that ad blockers operate based on filter lists targeting specific domains, script patterns, and even CSS or HTML element names is crucial for both users and developers to diagnose and potentially mitigate content blocking issues.
What email marketers say
10 marketer opinions
Website pages frequently fail to load or display content for users with ad blockers primarily because these tools block scripts, network requests, or content elements that they mistakenly identify as ads or trackers. This often results from broad filter lists targeting specific domains or code patterns, inadvertently affecting legitimate website components. Moreover, some websites now implement anti-adblock technologies that actively prevent content display if a blocker is detected, compelling users to disable them for access.
Key opinions
- Script and Network Blocking: Ad blockers commonly prevent website content from displaying by blocking essential JavaScript files, such as those used by Marketo forms, and network requests directed to domains frequently associated with advertising or tracking.
- False Positives in Filter Lists: A significant cause of content failure is the 'false positive,' where ad blocker filter lists mistakenly identify legitimate website elements-including CSS classes, IDs, or content-loading domains-as advertising material due to similar naming conventions or shared hostnames.
- Anti-Adblock Measures: An increasing number of websites deploy anti-adblock technologies or scripts that detect the presence of ad blockers. Upon detection, these sites can actively prevent content from loading or display a message, effectively compelling users to disable their blockers for access.
Key considerations
- Website Development Strategies: For website developers, it's vital to consider how content is loaded and which third-party scripts are employed, as 'dumb and ajaxy' methods or complex scripts sharing domains with ad services can be inadvertently blocked. Designing content to avoid patterns that mimic ad elements can help ensure better deliverability.
- User Troubleshooting and Access: Users can often resolve page loading issues by temporarily disabling their ad blocker. Additionally, website providers sometimes offer direct links to content, such as PDF versions of whitepapers, which can bypass blocked forms or scripts.
- Understanding Ad Blocker Mechanics: Both users and developers benefit from understanding that ad blockers use evolving filter lists. These lists identify and block elements based on domains, script patterns, and even CSS classes or IDs. This knowledge is key for diagnosing and mitigating content blocking issues.
Marketer view
Marketer from Email Geeks explains that the website page is likely not loading due to a common ad blocker like uBlock Origin blocking the Marketo forms JavaScript. He confirmed that disabling the ad blocker allowed the page to load immediately and provided a direct link to the content for an alternative way to access it.
21 Jun 2024 - Email Geeks
Marketer view
Marketer from Email Geeks explains that JavaScript from Marketo forms often falls into privacy default lists, causing them to be blocked. He suggests that users can often inspect the HTML to find the resource behind the form and provided a direct PDF link to the whitepaper, bypassing the blocked form.
2 Apr 2022 - Email Geeks
What the experts say
1 expert opinions
Website pages can fail to load or display content when ad blockers are active, as illustrated by a user's experience where uBlock Origin prevented a page from loading in Chrome and Safari, resulting in a persistent spinning red circle. This issue, however, did not occur in Internet Explorer, highlighting how ad blocker interference can be specific to both the blocking tool and the browser environment.
Key opinions
- Ad Blocker Direct Interference: Ad blockers, such as uBlock Origin, can directly prevent legitimate website content from loading or displaying correctly, even causing persistent loading animations like a spinning red circle.
- Varying Browser Performance: The impact of an ad blocker can be browser-specific, meaning a website might fail to load in one browser (e.g., Chrome, Safari) while functioning perfectly in another (e.g., Internet Explorer) without the same ad blocker or its corresponding filter lists active.
Key considerations
- Troubleshooting Page Load Issues: When a website page fails to load or displays unusual behavior like a persistent spinning icon, users should consider their ad blocker as a potential cause. Temporarily disabling the ad blocker can often resolve these issues.
- Browser-Specific Ad Blocker Impact: For users and developers, recognizing that ad blockers may behave differently across various browsers is crucial. A page failing in one browser due to an ad blocker might load perfectly in another where the blocker is not present or less effective.
Expert view
Expert from Email Geeks initially reported that a website page was not loading, displaying a giant spinning red circle. She later confirmed that her ad blocker, uBlock Origin, was preventing the page from loading correctly in Chrome and Safari, although it worked in Internet Explorer.
31 Mar 2023 - Email Geeks
What the documentation says
5 technical articles
Ad blockers are a significant reason why website content may not fully load or display, even when content is legitimate. These tools, including browser-native protections like Firefox's Enhanced Tracking Protection and Brave Shields, alongside popular extensions such as uBlock Origin and AdBlock Plus, operate by filtering out elements they identify as ads or trackers. This often results in essential scripts, network requests, or even images being inadvertently blocked if they share naming conventions, domains, or code patterns with advertising components, preventing the page from rendering correctly.
Key findings
- Diverse Blocking Methods: Ad blockers like Firefox's Enhanced Tracking Protection, Brave Shields, uBlock Origin, and AdBlock Plus universally prevent website content from loading by blocking scripts, network requests, and other elements identified as advertising or tracking, even when they are crucial for page functionality.
- Accidental Content Suppression: A common issue is when ad blocker filter rules inadvertently hide or prevent the loading of non-ad content. This occurs if legitimate content, images, or CSS elements contain names, IDs, or URLs that match patterns in the ad blocker's filter lists, for example, containing terms like 'ad' or 'banner.'
- Broad Filter List Impact: Browser-level ad blocking and third-party ad blockers rely on extensive blocklists targeting known ad domains, scripts, and trackers. If a website relies on resources served from domains present on these blocklists, or if its scripts are misidentified, essential content or functionality can fail to load.
Key considerations
- Website Design Principles: Developers must consider that reliance on third-party scripts, cookies, or cross-site requests, especially if these resources share hostnames or code patterns with advertising elements, can lead to their essential content being blocked by ad blockers.
- User Control and Adjustment: Users experiencing incomplete page loading or display issues due to ad blockers often have the option to temporarily disable the blocker or adjust its specific settings for a given website to restore full functionality.
- Potential for Misidentification: Understanding that ad blockers apply broad filtering rules based on patterns, not just direct ad content, is crucial. This explains why legitimate content can be mistakenly flagged and blocked if it resembles advertising components.
Technical article
Documentation from Mozilla Support explains that Firefox's Enhanced Tracking Protection, which blocks trackers and scripts, can interfere with website functionality if the site relies on these elements for content display or interactive features.
9 Jul 2024 - Mozilla Support
Technical article
Documentation from GitHub - uBlock Origin Wiki shares that websites can break due to uBlock Origin blocking essential scripts or network requests, or applying aggressive cosmetic filters. This often occurs when legitimate content shares hostnames or code patterns with advertising elements.
11 Jun 2025 - GitHub - uBlock Origin Wiki
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