Just thought I’d chime in – had the same problem, file exists, but the plugin reported the file didn’t.
Did a bit of digging in the code, the $file_path variable used when submitting the update form wasn’t taking into account my subdomain.
I changed the dedo_root_dir() function to use $_SERVER['REAL_DOCUMENT_ROOT'] instead of $_SERVER['DOCUMENT_ROOT'] and this fixed the problem.
Ryan
