Can't run screen due to "cannot open terminal '/dev/pts/1' - please check" error

Turns out the problem was that I ssh'ed into the machine as root, then changed to the user kramer65 with su kramer65 and then tried to run screen, where screen can only be run by the user that logs in using ssh. So after I added kramer65 to the sudoers file with usermod -aG sudo kramer65 I could ssh into the machine as kramer65 and run screen with a big smile.

There is a way around this without resorting to adding the user (kramer65 in this example) to the sudoers file. If you run script /dev/null right before attaching a screen session (or creating a new screen session), you should then be able to run your session without that error.