Site Health Monitoring
Issue Types
Every problem that Site Health Monitoring can find, grouped as in the Problem filter, with its typical severity and what it means for your site.
This page lists the issues that Site Health Monitoring can open. The groups are the same as the groups in the Problem filter on the Overview.
Each issue panel in the app explains Why it matters and How to fix the problem, with steps for your site.
The severity in these tables is the typical severity. VitalSentinel can raise the severity of an issue when the problem gets worse, for example when it spreads to more pages. The issue History then shows an event such as "Raised from High to Critical".
Indexability
Problems that can stop Google from indexing your pages.
| Issue | Typical severity | What it means |
|---|---|---|
| Noindex added | Critical | Pages got a noindex tag, so Google removes them from search results. |
| Robots header added | Critical | An X-Robots-Tag HTTP header now tells Google to remove pages or to ignore their links. You cannot see this header on the page. |
| Noindex added by JavaScript | Critical | A script adds noindex. The HTML source looks correct, but Google still removes the page. |
| Canonical points to another page | Critical | The canonical names a different page. Google can show that page instead. |
| Many canonicals point to one page | Critical | Many pages name the same canonical. Google keeps only that one page. |
| Canonical points to wrong domain | Critical | The canonical names a test site, a different site or the HTTP version. |
| Robots.txt blocks Google | Critical | A robots.txt rule blocks Googlebot. Pages can disappear from search. |
| Canonical removed | High | The page has no canonical. Google must guess which of the similar addresses to show. |
| Robots.txt failing | High | robots.txt returns server errors. Google stops crawling your site until it can read the file. |
| Noindex removed | High | A page type that you hid on purpose lost its noindex tag. |
| Page over Google's size limit | High | The HTML, or a script or style file, is larger than 2 MB. Google ignores the content after that limit. |
| Nofollow added | High | A nofollow robots tag is on a page type. Google does not follow its links. |
| Sitemap lists non-indexable pages | Medium | The sitemap lists pages that redirect, return errors, are noindex or name a different canonical. |
| Robots.txt sitemap line lost | Low | The Sitemap: line in robots.txt is missing or incorrect. |
Errors and redirects
| Issue | Typical severity | What it means |
|---|---|---|
| Pages returning server errors | Critical | Pages return a 5xx error. Visitors and Google get no content. |
| Pages not found | Critical | Pages that worked before now return "not found". |
| Pages redirect to homepage | Critical | Pages redirect to the homepage. Google can treat them as "not found". |
| Not-found pages served as normal | Critical | Pages show "not found" content but return a normal status (soft 404). |
| Same page at many addresses | Critical | Many addresses return the same page. |
| Error screens served as normal | Critical | Error or maintenance screens return a 200 status. |
| Redirects added | High | Pages that worked before now redirect, without a plan. |
| Redirect loops and long chains | High | A redirect loop never ends. Long chains make pages slow and use crawl budget. |
| Temporary server errors | High | Pages fail only some of the time. |
| Duplicate text across pages | High | Pages are almost the same. Google keeps only one of them. |
| Redirects sent to one page | High | Many old pages redirect to the same page. |
| Browser redirects added | High | Pages redirect with a refresh tag or a script, not with a server redirect. |
Rendering
Problems with how your pages show their content.
| Issue | Typical severity | What it means |
|---|---|---|
| Page content lost | Critical | Pages show much less text than similar pages. |
| Page text missing from HTML | Critical | The text appears only after JavaScript runs. Many crawlers, including AI crawlers, see an empty page. |
| Page renders blank | Critical | The page shows nothing. |
| Menu and footer links removed | Critical | The navigation lost its links. |
| Product or post list empty | Critical | A listing page shows an empty list. |
| Page tags rewritten by JavaScript | High | The title, H1, canonical or robots tag in the HTML is different from the tag after JavaScript runs. |
| Robots.txt blocks CSS and JavaScript | High | Google cannot load the style or script files of the page. |
| Files failing to load | High | Images, scripts or styles do not load. |
| Garbled text | High | The page uses the wrong character encoding. |
| JavaScript errors increased | Medium | More script errors occur. They can break menus, forms or checkout. |
| Top images not loading | Medium | Lazy-loaded images do not load and leave empty spaces. |
| Broken images | Medium | Images do not load. |
SEO elements
| Issue | Typical severity | What it means |
|---|---|---|
| Main heading missing | High | The page has no H1. |
| Page title removed or replaced | High | The title is empty, generic or the same as on other pages. |
| Language links removed | High | The hreflang links are missing. |
| Page language setting changed | High | The lang attribute of the page changed. |
| Structured data removed | High | A structured data type is missing. Rich results can stop. |
| Product markup missing required fields | High | Product markup has no name, price or currency, or no offers, review or rating. |
| Structured data unreadable | High | VitalSentinel cannot read a structured data block. |
| Viewport tag removed | High | Phones show the page zoomed out. |
| Canonical points to a broken page | High | The canonical target redirects, returns an error, is noindex or names a different canonical. |
| Language links broken | High | hreflang targets fail, are noindex or do not link back. |
| Conflicting canonical tags | High | Canonicals in different places of the page do not agree. |
| Many pages share one title | High | Many pages have the same title or H1. |
| Head tags in body | High | An element ended the head section too early. Google can ignore the title, canonical, robots tag or hreflang. |
| Placeholder text shown | High | The page shows "lorem ipsum" or template code. |
| Meta description removed or replaced | Medium | The description is missing or the same as on other pages. |
| Conflicting language settings | Medium | The declared language, the hreflang links and the language of the text do not agree. |
| Social sharing tags removed | Medium | Open Graph or other social tags are missing. This has no effect on rankings. |
Security
| Issue | Typical severity | What it means |
|---|---|---|
| Pages downgraded to HTTP | Critical | Pages redirect to HTTP or name an HTTP canonical. |
| Test site address exposed | Critical | Pages point to a staging or test site. |
| Hidden links or spam found | Critical | The page has signs that someone hacked the site. |
| HTTP files on HTTPS pages | High | HTTPS pages load files over HTTP (mixed content). |
| Content type or compression changed | High | The server does not send the page as HTML, or sends it without compression. |
| Security policy blocking content | High | The Content Security Policy blocks files that the page needs. |
| Security header weakened | Medium | A security header is missing or weaker. |
Performance
| Issue | Typical severity | What it means |
|---|---|---|
| Slower server response | Medium | The server takes more time to respond. |
| Page got heavier | Medium | The page size increased a lot. |
| Compression lost | Medium | The server stopped compressing the page. |
| New blocking script | Medium | A new third-party script blocks the page from showing. |
| Page caching lost | Low | Browsers and CDNs cannot cache the page now. |
Links and crawl paths
| Issue | Typical severity | What it means |
|---|---|---|
| Internal links with parameters | High | Internal links include parameters such as ?sort=, UTM tags or session IDs. |
| Menu or footer link broken | High | A link in the menu or footer of all pages is broken. |
| Nofollow added to internal links | High | Links to your own pages got nofollow. |
| Pagination links removed | High | List pages lost their pagination links. |
| Links to removed pages | High | Internal links go to addresses that now return "not found". |
| Menu or footer link removed | Medium | A page is no longer linked from the menu or footer. |
AI crawler access
Problems that can stop AI crawlers from reading your site. See also AI Readability.
| Issue | Typical severity | What it means |
|---|---|---|
| Robots.txt blocks AI search bots | High | robots.txt blocks AI search crawlers, for example the crawlers of ChatGPT search or Perplexity. |
| AI bots refused by server | High | Your server, firewall or CDN turns away verified AI crawlers. Needs Server Log Monitoring. |
| Snippet limits added | High | Robots tags limit the snippets that search and AI tools can show. |
| AI bot crawling dropped | Medium | AI crawlers stopped visiting. Needs Server Log Monitoring. |
| Slow responses to AI bots | Medium | Your server is slow to answer AI crawlers, so they stop. Needs Server Log Monitoring. |
| AI bot access changed | Low | The robots.txt rules for AI training or AI fetch bots changed. |
| AI usage rules changed | Low | The Content-Signal or Content-Usage lines in robots.txt changed. |
| AI bot rules contradict | Low | robots.txt gives opposite instructions to AI crawlers. |
| Section skipped by AI bots | Low | AI crawlers never visit a section of your site. Needs Server Log Monitoring. |
AI readiness
| Issue | Typical severity | What it means |
|---|---|---|
| Internal links missing from HTML | Medium | Links appear only after JavaScript runs. |
| Dates change without edits | Medium | The modified date changes, but the content does not. |
| Subheadings removed | Medium | The H2 and H3 structure of the page is gone. |
| AI discovery files broken | Low | llms.txt or the Markdown copies of your pages are broken. |
| Structured data missing from HTML | Low | Structured data appears only after JavaScript runs. |
| Bing slow to recrawl changes | Low | Bing takes a long time to visit pages that changed. Needs Server Log Monitoring. |
Our crawler is refused
| Issue | What it means |
|---|---|
| Our crawler is refused | Your site refuses the VitalSentinel crawler (403 or similar) on every page that VitalSentinel tried, including the homepage. Usually, a firewall or security plugin causes this. If your site opens in a browser, allow VitalSentinel Bot and check again. See Crawler access. |
| Robots.txt blocks our crawler | robots.txt keeps the VitalSentinel crawler out. This has no effect on Google, unless the same rule also names Googlebot. |
Issues from other modules
Site Health Monitoring also opens issues from the data of other VitalSentinel modules. The source module shows as a chip on the issue.
| Issue | Group | Source |
|---|---|---|
| SSL certificate expiring soon | Certificate | Uptime Monitoring |
| SSL certificate expired or invalid | Certificate | Uptime Monitoring. You cannot snooze this issue or mark it as normal. |
| Pages missing from Google | Google index | Indexing Monitoring |
| Rich result errors | Google index | Indexing Monitoring |
| Google chose another canonical | Google index | Indexing Monitoring |
| Poor page experience on phones | Page speed | RUM Monitoring or CrUX Monitoring |
| Poor page experience on desktop | Page speed | RUM Monitoring or CrUX Monitoring |
| Sitemap files unreadable | Sitemaps | Sitemap Monitoring |
| Many pages removed from sitemap | Sitemaps | Sitemap Monitoring |
| Robots.txt errors | Robots.txt | Robots.txt Monitoring |
| Robots.txt blocks Google | Robots.txt | Robots.txt Monitoring |
| Robots.txt blocks sitemap pages | Robots.txt | Robots.txt Monitoring |
Found on our first look
The first checks of a new site can find problems that were already there. Most of these issues have the same names as above, for example Main heading missing or HTTP files on HTTPS pages. Two have their own names: Page title missing and Noindex on pages getting clicks. These issues show the chip Already there when we started, so you can tell them apart from new problems.
Related
Overview
Read the Site Health Monitoring Overview - the Health score, score history, availability, issues, the pages VitalSentinel checks, and the page and issue panels.
AI Readability
Check whether AI crawlers can get into your site, whether they can read your pages without JavaScript, and the state of your llms.txt and other AI files.
