Some time ago my PHPBB forum got filled with spam. I managed to remove the spammy content but Google still knew the links to these pages. When Google came back to spider these pages, my forum didn’t manage to explain that this content was actually gone.
For humans it was clear that the content was gone, but Google was expecting an HTTP 404 error messages to come with the content. As a result Google kept coming back to these pages, spoiling my Google ranking. Through Google Webmaster Tools it’s possible to find issues with a website. As the visitors stayed away I decided to investigate what was going on and found out that I had 313 soft 404 errors on my forum with only 22 posts.
Searching on the internet what was going on, today I found that not providing missing content messages with an HTTP 404 error message was a know bug for PHPBB 3.0.x. Fortunately it was solved with version 3.0.8 which I installed 2 days ago…
So now it’s just waiting for the Google spider to drop by and have it find out that the removed content indeed is gone.
Update December 4th: 4 days later the number of soft 404 errors decreased to 264. So it’s working!