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NX TroubleShooting

Make sure to check out the "Tutorial"


Supported Versions of NX Player

You need the latest NX Player (5.0.63 or later), please refer to the Tested Player Page for downloading instructions. If you are getting errors like "Can't start the CUPS server", you will need to upgrade your local NX Player.

Connecting to NX

If you are having trouble connecting to NX, please can try these steps:

  1. Log into to clear any login failures. Access to NX uses your NERSC user name and password. If your password is mistyped five times, NERSC will lock you out of their systems. Logging into will automatically clear these failures. This will also let you know if your password is expired (which would prevent you from accessing NX, among many other things). Also note that if you change your password on NERSC systems, this will not automatically propagate to the NX password cache! 
  2. Re-download the NX configuration file. You can find the new configuration file at this link. NX will often "update" the configuration file to try to save your settings and sometimes this file can get some bad settings. You must have the new NX player AND the new configuration file to connect to the NX service.
  3. Try to ssh directly to the NX server. You can do this with the command "ssh <nersc_username>" and your NERSC user name and password. If your access to the NX server is blocked by a local firewall or something else, you will also not be able to connect with the NX client.

If you've tried these steps and still cannot connect, please open a help ticket. In this ticket, please include the following information:

  • The type of system you're trying to connect from (i.e. Mac, Windows, Linux, etc.).
  • A screen capture of the error you get (if possible).
  • A tarball of the NX logs. You can find instructions for how to bundle your NX logs on the NX website.

Configuring the NX Environment

Font size is too big or too small

To change the font size inside your terminal: In the menu of Konsole Application, choose "Settings"->"Manage Profiles", then click "Edit Profile...", now you can change the font size in the "Appearance" tab, after changing, click "OK" until you are back to the terminal. Now every new terminal window you open will have the new font size. 

To change the font size of your menu bars/window titles: Right click on an empty desktop then choose "Konsole", inside the Konsole, type "kcmshell4 fonts". Then you have a dialog box to change your font size. 

Resizing the NX screen

With the latest NX Player (5.0.63 or later), the most efficient way is to enable "Remote Resize" in the NX menu:

  1. Connect to NX
  2. From the desktop, bring up the NX player menu with a hotkey: Mac: Ctrl+Option+0, Windows: Ctrl+Alt+0, Linux: Ctrl+Alt+0
  3. Choose the "Display" submenu, then toggle the "Remote Resize" button. You can also choose "Change Settings" to manually change the resolution.

Emacs complains about missing fonts and shows white blocks

This is due to a problem with font server. Please use the following command instead:

emacs -font 7x14 

Keypairs and NX

The NX server acts as a gateway to all other NERSC systems. Users access other NERSC systems via SSH with their NERSC user name and password. The global home directories are not mounted on the NX servers, so if you want to use SSH keys on NX, you will need to generate a separate keypair.

Generating a Keypair

SSH Agent requires a keypair to function. The first time you click an item on the "NERSC Systems" menu the keypair is created and installed. You need to provide a password to encrypt your private key. This password can be different from your NIM password. You can generate a keypair by selecting the "(Re)generate Key Pair" menu item. If you have an existing keypair, this option will overwrite it. Once you've generated a keypair, you will need to upload the public key to NIM. This keypair will be good for 12 hours. You'll need to refresh it if it expires. You can do this by selecting the "Renew NX SSH Keypair" from the menu at the lower left hand side.

Suspending or Terminating a NX Session

When you close the NX window (e.g., by clicking the "cross" button) a dialog box will appear providing the choice of either suspending or terminating the session.

  • Suspending the session will preserve most running applications inside the session intact and allow you to reconnect to the session at a later time.
  • Terminating the session will kill all the running applications inside the session and all unsaved work will be lost.

If you lose your connection to the NX server (e.g., if your internet connection is lost) NX will automatically suspend the session allowing you to reconnect to the same session while keeping the running applications intact.