Let me guess, you just moved servers or directories, right? Fortunately it’s an easy fix.
Cake keeps caches of computationally expensive data in order to reduce CPU and memory use and speed your applications up. The downside is occasionally, such as after a server move, Cake caches something you really don’t want cached. In this case the absolute pathname to the CakePHP router.php file.
Fortunately the solution is easy. Just clear your cache by deleting all the files in tmp/cache and tmp/cache/models. The problem should instantly be gone.