Cannot Upgrade to 4.6

Hello,
Thanks for your time. I hate updating my site, last time I had a fatal error and had nothing for a few days until I asked for and received info on how to get it “back”

This time, I deactivated all the widgets, updated the backup widget (which backed the site up again) and attempted to update to 4.6.

I received this error message:
“The update cannot be installed because we will be unable to copy some files. This is usually due to inconsistent file permissions.: wp-admin/js/inline-edit-tax.min.js”

Any suggestions on what this means? I sure would appreciate the assistance.

I would never had messed with it but I am trying to make the site mobile friendly per Google. I thought I had a widget to make it mobile friendly. Apparently, not friendly enough.

Thanks!