In recent versions, MySQL runs in Windows as a user name "Network Service". To run Load Data Infile on an input file in c:\in, Network Service needs privileges in that folder:

1. In Windows Explorer, navigate to c:\in, right-click, and select the Security tab.

2. If Network Service is in the Groups or User Names list, click on it to ensure it has Read/Write permissions. If not, click on Edit, then Add, enter "Network Service" as the object name, click on OK, and check permissions as above.