I hit upon this error :

Cannot open your terminal '/dev/pts/0' - please check.

after being logged in under root and su to a user profile;

su user

and then willing to resume a screen :

# screen -r copy.pid
Cannot open your terminal '/dev/pts/3' - please check.

The issue is resolved using :

script /dev/null

I previously had similar issues, but this was using lxc-attach. See this previous post.