We are unfortunately unable to assist with upgrades from the 3.x platform, as we have no provided support for that item for a long long time now. However with this, the reality is its something you need to contact your hosting company on anyway. The folder is unable to be written to by our system, which is an issue on your hosting.
I can certainly move this to our community support for you, as others may have come across similar issues when upgrading from 3.x., but it does look to be hosting there.