cannot connect to X server / cannot open display


You receive the following message after entering a command to bring up a graphical window

cannot connect to X server cannot open display


This can happen due to multiple reasons:

  1. Reason: Your SSH client software does not support graphical display by itself (e.g. SecureCRT or PuTTY).
  2. Reason: You did not enable X11 forwarding in your SSH connection.

    • Solution: If you are in a Windows environment, make sure that X11 forwarding is enabled in your connection settings (e.g. in MobaXterm or PuTTY). If you are in a Linux environment, try

      ssh -Y -l username hostname

  3. Reason: If you are trying to open a graphical window within an interactive PBS job, make sure you are using the -X option with qsub after following the previous step(s) for connecting to the front-end. Please see the example in the Interactive Jobs guide.
  4. Reason: If none of the above apply, make sure that you are within quota of your home directory.

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