The OneDrive Mapper tool will map a drive as drive letter K: within Windows Explorer to your OneDrive for Business storage, allowing you to copy files and directories from D: drive to the K: drive using Windows Explorer.

The OneDrive Mapper tool is called FormOneDriveMapper.exe and can be ran from S:\SLS\OneDriveMapper.

The biggest limitation to using the OneDrive Mapper tool is that very large files, over 4Gb in size, can’t be copied using this method.

In practise files greater than 512Mb will have an issue copying to OneDrive for Business using the OneDrive Mapper tool.
For very large files you will notice the file copy will reach about 99% before pausing and eventually it will timeout with an error.

If this occurs we would recommend you copy these large files using using Chrome.

See the video below showing how to use the OneDrive Mapper tool.

If you have used the Mapper tool when copying files from D: and the Desktop please ensure you are actually copying the files and not just creating shortcuts to the files.
Shortcuts will show within OneDrive as a type ‘Shortcut’ not ‘Microsoft Word Document’ or whatever type of file you had meant to copy.