I have the 1.13c version and use the same guide to install.
Until today, i was playing like a monkey, but some hours ago, i opened the launcher, it request to upgrade the client, clicked and happened what i told up here.

In any case, im downloading the 1.13d diablo posted in the guide (at 80kb/s it will take some hours more) to see if there's a versions mismatch that causes the issue.