Missing Controller

_Files_Controller could not be found

Additional Information

The system searched in the following paths:
- /home/stalfred/public_html/application/controllers
- /home/stalfred/public_html/core/libs/controllers

Request Information
controller: _files
action: ugd
params: 0 => a1be75_a4bff949b9b545a6ba67790b93d3d1e9.pdf
url: url => _files/ugd/a1be75_a4bff949b9b545a6ba67790b93d3d1e9.pdf