Container enter failed

Problem: VPS created succesfully and started. But when trying to do

vzctl enter 101 

you get

VPS enter failed(?)

Using strace, you see:

# strace -ff vzctl enter
....
fstat64(...st_mode=S_IFCHR|0620, st_rdev=makedev(136, 0)...) fail
....

Solution: Recompile the kernel with the following option:

CONFIG_LEGACY_PTYS=y