Mod_jk: Uri * is invalid. Uri must start with /

[Matteo Turra]

I have Apache/2.2.14 (Unix) and mod_jk/1.2.28 with a Tomcat 6.0.20 farm
in load balancing.

In the mod_jk.log I get a line like this each second.

[warn] map_uri_to_worker_ext::jk_uri_worker_map.c (962): Uri * is
invalid. Uri must start with /

I checked all the JkMount directive in the virtual host

Any suggestion?