Problems updating

I have been trying to update wordpress. When I try to update to 5.4.1 it will go through the process and then I get the following message :

The update cannot be installed because we will be unable to copy some files. This is usually due to inconsistent file permissions.: index.php

Installation Failed

This has been going on for a while.. It has caused JetPack to stop working…

The site still seems to be working fine, but would like to get it updated, as hopefully things will get better and I will get busy again…

any suggestions would appreciated, as I am really lost on things like this…
thanks

The page I need help with: [log in to see the link]