Unusual Situation - 100’s of Pages Being De-Indexed Every Few Hours

[stevenhold]

I’ve been building an authority site for the past several years and yesterday I noticed a handful of prominent pages were no longer indexed (including the site's homepage). Normally I would assume this was a side-effect of the recent algorithm update and figured I would give it a few days to work things out.

Today, I decided to check again and discovered that more pages were de-indexed overnight. So, I did one last check an hour ago and yup, pages are continuing to be de-indexed – including pages which I manually verified were indexed (and ranked) a few hours earlier.

The way I'm checking the index status is by searching Google for "site:url" and "info:url" and neither have any results.

I’m trying to understand what exactly could be causing this mass de-indexing, and any help would be greatly appreciated.

Here are some details about the site:

• The site is an authority site about animals
  
• Our priority with the site is rich content and user experience
  
• We don't have the site fully monetized. None of the pages have more than 3 ads.
  
• All content is unique and high quality written by writers we hired in-person (no outsourced writers)
  
• The page load time is about 600ms on fast internet connections (Google's crawler states the average is 198ms)
  
• We don't use any 3rd party plugins. Everything is written in PHP and vanilla JS
  
• We have not switched to https yet, though we are planning on doing this in May
  
• The site is responsive (i.e. does not have a separate version for Mobile/Desktop)
  
• There are no forums, chat rooms, or public discussions on the site
  

SEO Info:

• All links pointing to the domain were done at the choice of our visitors. Our SEO strategy has been if we have the best content people will link to it, so we haven't built any links to our site.
  
• We have Webmaster Tools, Sitemaps, and everything else setup correctly
  
• We are not using any blackhat techniques.
  

Index Info:

• Webmaster Tools states that 16,000 pages are currently indexed
  
• Yesterday doing a "site:url" search only showed 15,500 pages are indexed
  
• Just now doing a "site:url" search shows that 14,500 pages are indexed
  
• The pages which are de-indexed have been indexed in Google for anywhere from 1 month to 4+ years
  

I've been an internet marketer for 15 years and a full stack developer for 5 years and I am currently stumped. There is no pattern for which pages are being de-indexed (e.g. not a specific category of pages are being de-indexed, rather it seems random). The site follows all the recommendations in Google's Webmaster Guidelines and does not have any warnings in Webmaster Tools.

The only thing I can think is the site is being re-evaluated by some algorithm update and will continue to behave unexpectedly until the update is complete? However, whenever this has happened with sites in the past, the pages remained indexed. Generally from my experience, whenever a site's homepage is de-indexed it means something with the site has severely violated Google's policies and the site is no longer indexed, so as you can imagine I want to make sure this is not the case.

I don't want to publicly display the URL of the website, but I will share the domain with anyone via PM if evaluating the site will be beneficial. Of course, any help would be greatly appreciated (and will help me sleep this evening), so if you have any questions I will try to answer promptly.

Thanks again.

[stevenhold]

Do you think that changing the CSS last week could have somehow triggered this? I know this sounds far fetched, but hear me out. I just checked a "cached" page for the site on Google and it had text content hidden behind a nearly full-page modal/lightbox window. Well, we updated the HTML and CSS stylesheet a week ago to change how the lightbox window works - and it works perfectly with no issues. However, if you use the old HTML with the new CSS stylesheet it will force an empty lightbox to hover over the text content.

So, what I'm thinking is, what if Google's bot cached the HTML code and not the CSS. That would mean that if the bot attempted to re-render the page at a later date, the new CSS would block all the text content and make it appear the page would be keyword stuffing (which the site is not doing).

I used the tool in Google's webmaster tools to "Fetch as Google" and it is showing the page without any issues, but the cached versions of the page (in Google's SERPs) all have the modal window blocking the text content. Another interesting thing is it seems the pages de-indexed first are pages which are crawled the most frequently. One of the first pages I noticed de-indexed was the site's index page and this morning all the new pages that were de-indexed happened to be the pages which received the most SERP traffic from Google. None of the pages which receive little traffic are de-indexed.

Anyway, I just updated the site to fix the lightbox window from blocking content just in case any bot is using cached HTML, so I'll see if that has any effect. By the way, Google now says the site has 14,300 pages in it's index (200 less than 2 hours ago). Hopefully this CSS fluke was the culprit...

[keyplyr]

I've seen indexed page count drop significantly and a few days later the number came back up and a few days after that all pages were back in the index. Never did figure it out. Scary when it happens though.

Currently, as we speak, Google is building the Mobile-first Index. [webmasterworld.com]

This could be a factor to what you're seeing.

[stevenhold]

Thanks for your response. Yeah, I'm hoping that it's it. All of Google's Webmaster Tools validation metrics indicate the site is compliant with no issues and no recommendations for improvement, however 2,000 additional pages were dropped from Google's index overnight so I'm still a bit stressed. The site's never had any indexing issues nor had any negative effects from search algorithm rollouts in the past, but I've experienced them with other projects so this is bringing back some memories.

It is nice that Google's newer Webmaster Tools console gives extra details about a domain's index status, however it tends to have a 5-7 day delay so worst case scenario I have to wait another 5 days to see what those reports indicate. Other than that, I'm still trying to figure this out so I'm open to all feedback.