Google AI Search Called This Site Offline - John Mueller Reveals the Overlooked Cause

In February 2026, Google Search Advocate John Mueller clarified why Google AI Search had indicated that a website was offline. He traced the message to the site's use of JavaScript for content delivery, following a discussion sparked by a Reddit post.

Key Details

A website owner reported that Google AI Search displayed a notice saying their site was offline, stating it had been down since early 2026. The owner documented the issue in a blog post and shared it in a Reddit thread.

Mueller responded publicly in that Reddit discussion after reviewing the website. He found that the page initially served placeholder text in the HTML indicating the service was "not available". JavaScript later replaced this text for users whose browsers executed the script.

According to Mueller, clients that did not run the script continued seeing the original "not available" message. He advised against using JavaScript to switch text from "not available" to "available" in this way and recommended serving consistent content that does not depend solely on JavaScript text replacement.

• The HTML sent to browsers contained a message saying the service was not available.
• Google indexed that original HTML content without applying the JavaScript change.
• AI-powered answers drew on the indexed text, which described the site as unavailable.
• Mueller compared this pattern to attempts to change robots meta tags using JavaScript, which Google does not recommend.

For site owners, the case underscores the importance of keeping critical status messages and other key information in the initial HTML, rather than relying only on JavaScript to modify visible text.

Background Context

The website owner's blog post carried the headline "Google Might Think Your Website Is Down". It used phrases such as "cross-page AI aggregation" and "liability vectors" to describe the situation. Search Engine Journal reported that these phrases are not widely recognized technical terms in computer science.

In the post, the owner wrote that they were unaware of any special Google capability to detect downtime and noted that an internal service behind a login would not be visible to Google. Before Mueller's response, the owner made changes such as removing a pop-up, without confirming the specific cause of the problem.

The blog suggested that Google AI Search might assemble answers from a mixture of pages about a site, raising concerns that any on-page content could influence AI-generated responses, even when users ask unrelated questions. Search Engine Journal reported that its understanding of Google's AI Search is that its summaries are tied to existing indexed content.

Source Citations

The details in this article are based on reporting by Roger Montti for Search Engine Journal in February 2026, along with public comments made by Google Search Advocate John Mueller in a Reddit thread. No additional statements from Google or the site owner were cited beyond those sources at the time of reporting.