Core issue
These error messages appear in the logs:
%KERNEL-1-CREATEPROCESSFAILED:Error in creating process: Unavailable free stack; stack type: 2; Name: tnetproc
%MGMT-2-SESSION_FAIL:Out of telnet processes. Try later.
The %KERNEL-1-CREATEPROCESSFAILED: Error in creating process: [chars]; stack type:[dec]; Name: [chars] error message indicates that the create process has failed; the system is out of processes. The Catalyst operating system allows a limited number of processes based on the number of stacks available. When stacks are unavailable, this message is generated. The first [chars] is the process ID, the [dec] is the stack type, and the second [chars] is the process name.
CatOS switch allows only a limited number of processes with a type 2 stack, for example, Console, snmpdm, VtpRx, THREAD, telnet145, in the system. The maximum number of processes with a type 2 stack is 13. Telnet or Secure Shell (SSH) is one of the processes which require a type 2 stack. When all type 2 stacks are used, any attempt to connect through Telnet results in this error message.
This possibly happened because the old Telnet or SSH sessions did not timeout on the switch and consume the process.
The %MGMT-2-SESSION_FAIL (x1): Out of [chars] processes. Try later error message indicates that no more SSH or Telnet sessions can be established. [chars] is the process type, this error message is a consequence of the first one.
Resolution
In order to resolve this issue, issue the show users command in order to check how many Telnet sessions have opened for the switch. Disconnect the telnet sessions opened by the remote device with the disconnect {ip_address} command.
