"The site with the id {GUID} could not be found" and BLOBCache

My own memo. Nothing I myself found.
Anyway it was really hard to figure out. But I was lucky that it happened in our testing environment. So I did not have to start crying yet.

The problem was the following.
I was getting “The site with the id {GUID} could not be found” error to get some css files from Style Library. But only on the extended web application, and futhermore, only when a user logs in to the site. # Our site accepts anonymous visitors too.

I re- extended the web app, re-restored the data from our production site. Nothing helped. # I did not have the problem on the production site.

As always, I went to the net for some help, a hint at least. But this time I did not think I would find anything helpful. I was believing that the content database might have been corrupted somehow, or something…

However, there are people who had the exact same problem, and have overcome it.
http://blogs.msdn.com/joshuag/archive/2008/05/22/filenotfoundexception-the-site-with-the-id-guid-could-not-be-found.aspx

This was a big help. I did not even think about the cache.
Unfortunately, however, the solution did not work for me.

But I know now all I need to know is how to clear the cache. And found this http://blogs.pointbridge.com/Blogs/monnette_jeff/Pages/Post.aspx?_ID=15.

More (seemingly) in depth explanation can be found at http://sharepointinterface.com/2009/06/18/we-drift-deeper-into-the-sound-as-the-flush-comes/.
I did not have anough patience to read it throughly though…

In short, the UI does not work for a farm like ours, and the stsadm solution (http://msdn.microsoft.com/en-us/library/aa622758.aspx) stinks.
We have only two front-ends. So I went for the manual flush.