How do you find the source of a 404

[TTS_Group]

I've recently noticed quite a sharp rise in the number of 404 errors on our site. Unsurprising really as we have just had a major upgrade of our site navigation. When looking in GA at the landing page stats the vast majority of them are from Google organic search. How do I find the source of the 404?

All help appreciated.

Thanks.

Jon

[maxweb]

Make sure you have google webmaster tools installed. On your dashboard, it will tell you if there are any crawl errors, click here to see where they are. Click on each link and it will give you the location of the URL and which pages are linking to it.

A quick solution would be to create 301 redirects for each page in your htaccess. However, it may be better in the long term to find all the pages linking to the missing pages and re-write them.

[GPainter]

http://www.screamingfrog.co.uk- is a great bit of software  or Xenu

They are free and can tell you 404 etc. on your page and you can 301 from there.

[KeriMorgret]

The Moz crawl will also identify 404s for you, and when you download the CSV, you can see the source of the 404.

[vmialik]

For the quickness/effectiveness it would be, these in order:

1. Xenu

2. Screaming Frog

3. 404 Redirected Plugin (if you are using Wordpress)

Also once done also check with Google Webmaster tools and Moz tools to see if you caught all of them, this also takes a bit longer to update, thats why I listed it here, but you can also start with theses as well. If these campaigns/profiles are setup.

[KBC]

But that are only the internal sources...? Not?

[GPainter]

Try Open site explorer and "link opportunities" for any pages that are 404 and have external links.  Webmaster tools will also show you pages that are 404 that have external links (though it doesn't show you the links) and Ahrefs has a similar tool