WebMaster Tools keeps showing old 404 error but doesn't show a "Linked From" url. Why is that?

[revimedia]

Hello Moz Community.

I have a question about 404 crawl errors in WebmasterTools, a while ago we had an internal linking problem regarding some links formed in a wrong way (a loop was making links on the fly), this error was identified and fixed back then but before it was fixed google got to index lots of those malformed pages.  Recently we see in our WebMaster account that some of this links still appearing as 404 but we currently don't have that issue or any internal link pointing to any of those URLs and what confuses us even more is that WebMaster doesn't show anything in the "Linked From" tab where it usually does for this type of errors, so we are wondering what this means, could be that they still in google's cache or memory? we are not really sure.

If anyone has an idea of what this errors showing up now means we would really appreciate the help. Thanks.

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[OlegKorneitchouk]

I've had those too and they are quiet annoying (love seeing 0 errors hehe). I just mark and fixed and hope it doesn't show up again (usually stops appearing after doing that once or twice).

If anyone has another other insight into this, please share!

[WilliamKammer]

I hate to speculate on anything involving SEO, but I've always taken those 404s as visits Google has been able to grab data for. If Webmasters is able to catch the data for a visit to a 404, it'll let you know about it.

What lead me to this cringe assumption cringe was how similar those 404s were to existing pages, like someone tried to type in a URL and got it wrong, or deleted some of it and hit "enter".

Take the info for what it's worth, which isn't fact, just an idea to get you rolling.

[JaneCopland]

Hi,

How long have these errors been appearing since you fixed the issue? It could be a case of Google looking for URLs on the site that it has seen in the past, even though there is no path to them anymore. With the pathway gone, it should stop looking, but I'm curious how long the issue has been fixed for?

[revimedia]

hi Jane, we've solved the cause of these errors more than 4 months ago at this point. There is no path to these urls anymore, but they keep showing up so it takes Google pretty long to clean up. And our estimate is that there about 400 more of these 404 errors so we still have some time to go I guess.

[JaneCopland]

Hi again,

Four months seems abnormally long, but it could have something to do with how many 404s are are - 400 is pretty high. Is this number at least going down every few weeks in WMT?

Cheers,

Jane

[revimedia]

Hi Jane, thanks for the follow up. Every time we see errors showing up in WMT (mainly 404's) we remove the URL's right away and indeed we see the errors going down every 4-5 days (under HTML improvements).

I am just surprised, that if we would not use the URL removal tool, how long it takes for Google to actually remove 404's from their index. I know the higher the PR, the more likely they crawl more often and the faster they remove these 404's I guess, but still.