If you have the plugin Wordfence installed as well as Yoast SEO, then you should probably know that the Yoast SEO and Wordfence plugins don’t play nice at all. Do not panic and throw things if you see the message “Your homepage cannot be indexed by search engines” after upgrading the Yoast SEO plugin, especially if nothing else has changed on your website’s back-end or even front-end since. There may very well be nothing wrong.
Both Yoast SEO and Wordfence are, independently, excellent plugins when it comes to doing what they’re supposed to do: in Yoast SEO’s case, it is helping make sure that your website is as indexable and rankable as possible; in Wordfence’s case, it is protecting the hell out of you from attacks, malicious software, and malicious logins. However, together, they don’t play nice on one instance, and one instance only: when Yoast gets updated, it throws out this whole boogaloo that “Your homepage cannot be indexed by search engines”.
I personally have WordPress set to update most of my plugins automatically, so sometimes I can go a little bit without knowing that Yoast has deemed my website unindexable, which will in turn definitely affect my page rankings on SERP’s. So, not cool, Yoast, not cool.
How to (permanently) fix this
There is, that I know of, no fix for this. Which is sad. I would like Yoast to know that this started only mid-2015, after one of its major updates which changed quite a bit in terms of layout on the post edit page and probably quite a lot in back-end coding. But, alas, I am no coder and I don’t want to go and play with Yoast SEO’s code. So hopefully they will fix this soon, because it is absolutely annoying, I’ll grant you that.
How to (temporarily) fix this
Very simple. First things first, log into your site’s WordPress account (if you haven’t already) and navigate to your Plugins page from the left sidebar menu. From there, click the Deactivate link (only temporarily! We’ll reactivate it in a jiffy!) under your Wordfence plugin.
Let the page reload on its own to mirror this request, and then navigate back to the Dashboard on the left sidebar menu. Click that Fetch the current status button on the Yoast SEO widget, and it will turn green. Huzzah!… but we’re not done. Once you have the green light, navigate right back to the Plugins page, and reactivate Wordfence Security.
Voilà! You’re done. Wordfence works, and Yoast is indexing your website again!
For some reason, Yoast can’t seem to allow your website to be indexed unless Wordfence is temporarily inactive. For now, the simple fix is to deactivate Wordfence temporarily so Yoast can fetch its status; then you may reactivate Wordfence. Weird, right?