Call a topic by using "?contenttype=application/pdf" creates the warning "unknown parameter name META{"form"} at /.../lib/Foswiki/Sandbox.pm line 283." on every call.
Apache error_log:
...
[Wed Nov 10 10:02:55 2010] [error] [client xxx] unknown parameter name META{"form"} at /xxx/lib/Foswiki/Sandbox.pm line 283.
-- SaschaVetter - 10 Nov 2010