It may be because
ptsfs isn't running.
ptsfs is running by
mount | grep pts
You should see something like this
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=620)
ptsfs isn't running then mount it manually, as root
$ sudo mount -t devpts devpts /dev/pts
and add the following line to
devpts /dev/pts devpts gid=5,mode=620 0 0
The reasoning behind this answer is explained here, gnome-terminal: There Was An Error Creating The Child Process For This Terminal,
This problem is related to devpts (also known as Unix98 pty naming)
file system. The devpts must be mounted on /dev/pts. Before opening
the pseudo-terminal slave, you or the process must pass the master’s
file descriptor. From the man page:
minor number 2, usually of mode 0666 and owner.group of root.root. It
is used to create a pseudo-terminal master and slave pair. When a
process opens /dev/ptmx, it gets a file descriptor for a
pseudo-terminal master (PTM), and a pseudo-terminal slave (PTS) device
is created in the /dev/pts directory.
FWIW, the above "gnome-terminal" link was linked to from an unrelated gnome-terminal bug logged on the Mint bug database, There Was An Error Creating The Child Process For This Terminal, however, the error in that was subtly different:
There Was An Error Creating The Child Process For This Terminal
Text was empty or contained only white spaces
This issue also occurs on Ubuntu, as referenced here, on Ask Ubuntu, How do I relaunch terminal?.
The solution to which could be either
To solve the problem : Click the profile preferences box, untick "run a custom command". Exit. Close the terminal and relaunch. Thats it.
or the answer to How do I relaunch terminal?
However, as this is a different error from your issue, it should probably be discounted. I only mention it as it was how I found the gnome-terminal ptsfs issue/solution.