Recently we had a client come to us with a situation where Google Webmaster Tools was reporting an ever-growing number of soft 404 errors. While there are many reasons for soft 404 errors to occur this situation had us puzzled for a few days until we figured it out.
In this particular instance we discovered the Soft 404 errors which Google was reporting were caused by old 301 redirects.
When we built and launched their new website we properly 301 redirected many of the old pages to the new pages as the URL structure was not ideal.
Fast-forward 16 months and enter some basic maintenance in response to panda/penguin updates which necessitated 404′ing and even 410′ing several of the newer replacement pages.
What we realized was that the old original pages which we 301 redirected to never pages which were now 404′d resulted in Google Reporting soft 404 errors which they attributed to the original page 301 redirected page.
Maybe this will help make sense of it:
www.site.com/oldpage 301 redirected to www.site.com/newoldpage
www.site.com/newoldpage was subsequently removed and 404′d
www.site.com/oldpage now reported as a soft 404 by Webmaster Tools.
The decision now is weather to 301 the original page to the replacement page or 404/410 it.
That we will leave up to you or feel free to contact us here at Search Marketing Group for Advice.