If the checkboxes within the WordPress Admin do not appear checked. You may need to verify that your Content-Security Policy (CSP) allows “data:” as a source.
default-src data: 'self' *.googleapis.com *.gstatic.com;
While doing routine WordPress updates I came across this error:
cURL error 18: transfer closed with X bytes remaining to read
After some investigation I found that my hosting server was unable to download files. Much of the advice I found suggests issues with cURL, PHP, or WordPress. If possible I advise checking the host server first. Verify that it can download the update file.
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 twenty one year's experience in systems administration, computer programming, requirements gathering, customer service, and technical support.