File.Copy Method (String, String)
When it is called by trusted applications, copies an existing file to a new file. Overwriting a file of the same name is not allowed.
Assembly: mscorlib (in mscorlib.dll)
The caller does not have the required permission.
sourceFileName or destFileName is a zero-length string, contains only white space, or contains one or more invalid characters as defined by GetInvalidPathChars.
sourceFileName or destFileName specifies a directory.
sourceFileName or destFileName is null.
The specified path, file name, or both exceed the system-defined maximum length. For example, on Windows-based platforms, paths must be less than 248 characters, and file names must be less than 260 characters.
The path specified in sourceFileName or destFileName is invalid (for example, it is on an unmapped drive).
sourceFileName was not found.
An I/O error has occurred.
sourceFileName or destFileName is in an invalid format.
For more information about trusted applications, see Trusted Applications.
Silverlight for Windows PhoneThis member has a SecurityCriticalAttribute attribute on Silverlight for Windows Phone, because the attribute was present in Silverlight 3. This attribute restricts this member to internal use. Application code that uses this member throws a MethodAccessException.
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.