It's a tricky lesson to learn as Google often release posts and content which over-burdens developers with false-confidence (it's not the developer's fault). Basically, website owners and company owners often ask broad brush questions and pressure Google to respond with simple, succinct answers (like in Matt's old Webmaster videos).

Google cave into this pressure and say stuff like "yeah doing redirects for your migration is good", but in some (not all) of their published content, completely neglect to mention that some redirect types are more worthy than others within the context of certain situations.

Developers read posts written by Google and just think "ok fine that's how it is now so we just do that" and, of course - unless you make a livelihood studying all this stuff, you end up pretty far wide of the mark.

I recently answered this question by a webmaster whom had taken it for granted that, because Google 'can' crawl JS they always will (under all circumstances). He made a move in terms of technical on-site architecture and saw loss as well

Just ask the guys who know!

And yes, do the redirects, you may as well. You might still get something back from it (probably not a lot though)

No, none whatsoever. The old TLD bonus debates drew an accurate correlation but completely inaccurate causality

People thought:

1) I see lots of EDU sites

2) They rank really well

3) If I make an EDU it will rank well

... WRONG! Google aren't that stupid. Otherwise all webmasters would now be using EDU domains and all other domains would be pointless (which would be a weird internet to live on)

The truth was actually this:

1) EDU TLDs (Top-Level Domains) tend to be chosen by educational bodies or organisations

2) Such organisations are usually run by educated people and academics

3) One thing those people are good at, is creating really strong (in-depth) accurate content

4) As such many EDU sites naturally became prominent, because of Google's normal ranking rules (not some weird EDU TLD bonus scheme)

If you're looking for quick and easy answers in SEO, you're gonna have a bad time

Site speed impact is where I see this becoming a real problem, unless the setup is done correctly

404s are usually for pages that 'don't exist' so that's pretty usual. This is either:

1. somewhere on your site, links are being malformed leading to these duff pages (which may be happening invisibly, unless you look deep into the base / modified source code). Google simply hasn't picked up on the error yet

2. something is wrong with Rogerbot and he's compiling hyperlinks incorrectly, thus running off to thousands of URLs that don't exist

At this juncture it could be either one, I am sure someone from Moz will be able to help you further

That sounds like a negative SEO attack, let me explain that for you. In the past, the volume of backlinks mattered more than their quality (before PageRank was refined more, before Google's Penguin algorithm updates)

As you can imagine, this was heavily abused so Google took measures to counteract the worst of the SEO industry. They created clever algorithms which attempted to determine, whether links had been built 'just for SEO' or whether the links in question were truly relevant. For sites attempting to manipulate Google's rankings, they de-valued the linking sites or in the worst cases, applied manual penalties - nullifying all their rankings

Again the industry adapted to Google's changes. People learned that if they created links which 'looked like' they had been manufactured to raise Google rankings, they could penalise the site they were pointing to (enter: Negative SEO)

Google's algorithms have come on since then but IMO still take a harsh line and have a very difficult time distinguishing between manipulative links and negative SEO links

As such, it's wise to take action on this kind of stuff. Whilst a disavow project may slightly lower rankings a small amount (as an SEOs view of what's a bad link, is never 'perfectly' aligned to Google's view) - it's still worth doing. If you ignore such things for too long and they mount up, instead of seeing a small dip - you can lose ALL your rankings (when Google's algorithms fail to evaluate the links correctly)

Personally I'd take action, especially as some links are porn related ('bad neighbourhood' links)

The best thing to do is download all links from all the main backlink sources (Ahrefs, Moz, SEMRush, Majestic SEO). Once this is done you can use something like URL profiler to set metrics against each link (adding of course, your referral traffic data from GA). You can weight or balance these metrics in a new column in Excel, and then evaluate which links are good or spammy

At the end of the process, you have a list of domains to disavow. At Effect, we've got really good at this actually. Even though we always tell clients they could see a small dip in results, in many cases they don't even see that. Then they can have peace of mind ,that their backlink profile (at least for a few months, or couple of years) is 'insulated'

Email address is on our Moz community profile if interested

Google doesn't use rel=prev/next any more: https://searchengineland.com/google-no-longer-supports-relnext-prev-314319 - so forget about it unless you think it has benefits for crawlers other than Google

I would do the redirects properly, so redirect the old paginated URLs to the same page (paginated URL) on the new site

Google usually doesn't list paginated content but it can do sometimes. A good example of this is when you type really specific queries into Google and find that Google is linking to a topic on a forum. Quite often you'll see Google linking to paginated content there. Why? Because that specific page of the topic, is the part where the thread really gets answered (or gets its best insight). Maybe some people link to that page of that thread specifically, and it becomes more popular than the first page

In those situations, Google's usual view (that first page should be canonical) gets overridden. So whilst Google 'usually' makes the first page canonical, sometimes Google can change its mind if popularity metrics suggest a different paginated URL should be canonical instead

As such, you don't need rel=prev/next (which Google doesn't even use) and you don't need to put canonical tags on paginated content pointing to the parent (which might disable Google from overriding the default canonical URL). I would properly redirect all the old paginated URLs, to all the new ones - so Google doesn't get confused

Hard to tell what to do without seeing specifically where this error is coming up, but it usually has something to do with font sizes being too small on mobile devices. Mobiles have much more densely packed pixels on their screens (images are sharper, the pixels are smaller and more numerous). This means that 12 pixels (font-size) on desktop can look like 5 or 6 pixels on mobile devices (or even smaller)

This is why, with responsive design, many people don't specify a pixel-based font-size. They'll make the font size relative (rather than absolute) somehow, be that by calculating pixel width against screen width as some percentage, or by working with newer font-sizing specifications (there are many, and many ways to use them). It's all about inflating font-sizes on devices with more densely packed pixel screens, so that the fonts don't come out looking minuscule

Sometimes you can get errors where, even though the site's design is responsive, as someone was writing text in the CMS text editor - it appended styling info including the px font-size, which is then inlined (overruling all your perfectly thought out font-sizing CSS rules)

If it's not mobile related at all, it's likely that the font is just generally too small

No-followed links don't usually pass SEO authority across, negative or positive. Unless you begin to notice a specific and isolated impact on related rankings, I honestly wouldn't worry too much. No-followed links usually don't affect SEO (period)

You could always just disavow the domain(s) if you really wanted to, then even if they removed the no-follow tags you'd still be unaffected. In my opinion I wouldn't do anything if the links are all 100% no-followed anyway

Yeah definitely don't do it the other way around. To be honest if the landing pages are orphaned, Google probably won't rank them anyway. If Google 'is' ranking them instead of the other ones, the real question is why does Google find them more useful, and what can you add from the landing pages to the organic pages - to make them better!

Highly doubt that would be a reason to 'lose of lot of SEO ground'. If those URLs were 404-ing before, you had breadcrumb links to 404s and that's worse than breadcrumb links to 301s

The bigger problem was, you lost your category pages which got set to not visible. And by the way, even when you change them back to 'visible', if the 301 is still in effect - users and search engines still won't be able to access your category URLs (as they will be redirected instead!)

If the category pages have been restored and you're still redirecting them, yes that is a big problem. But it's not because you used a 301 in a link, it's because you took away your category URLs. That very well could impact performance (IMO)