While updating a WordPress site hosted on a Windows platform (Internet Information Server); I came across this error:
The update cannot be installed because we will be unable to copy some files. This is usually due to inconsistent file permissions.: wp-admin/includes/update-core.php
I confirmed the Application pool identity for the site had the appropriate permissions. After some reading related to the same error on an Apache web server I found the issue possibly due to the Read Only flag on some files or folders within the WordPress install folder.
I used the Windows property manager to ensure the Read Only flag for all files is UNCHECKED:
Cascade the setting to subfolders and files:
An information technology professional with nineteen year's experience in systems administration, computer programming, requirements gathering, customer service, and technical support.