I recently received repeated notices from Google saying my site has an increase in 403 authorization permission errors. Looking at the chart I see that starting on July 22 the errors are indeed increasing and are now at 1168 errors.
These errors seem to come from Google trying to access directories where there are no index files. There are other things in the directories: images for instance, or other directories. What I don't understand is that the "linked from" pages do not exist. They are always other directories, higher up, that contain either images or other directories too.
For instance access is denied to page www.example.com/exliibris/00/9b/88/
This directory contains some html files but no index.html
This directory contains only other subdirectories and no index.html.
This structure of the directories hasn't changed in years, but suddenly Google started inventing links that don't exist. The whole site is indexed by Atomz and there are no errors at all (or a few that we quickly find and fix).
The files that are in the directory at /00/9b/88/ are all accessible by "Fetch as Google".
Google fetches the html files. Google also shows in the results of the fetch, two other files I didn't ask for:
the home page
These two directories do have index files and they are the ones that are shown.
Now, if, behind the scene, Google just goes up the hierarchy and looks for index files in all directories including in /00/9b/ and in /00/, that is fine, but when there isn't one, it shouldn't report an error.
What can I do to stop getting these 403 authorization permission errors that don't mean anything, and don't correspond to any real links?