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How to troubleshoot Parallels Server VM VNC console java applet problems

Article ID: 5870, created on Dec 16, 2008, last review on Jul 16, 2014

  • Parallels Cloud Server
  • Parallels Server
  • Parallels Virtual Automation


  1. Before going any further check that you have the latest Sun Java(TM) plugin ( and JavaScript is enabled in your browser.

  2. Console is not responding sometimes:

    1. Connection problems:

      1. Connection error messages may indicate that VNC server for this VM is down - possible reason: VM is stopped or being restarted. Refresh page to check VM status and reconnect to Remote Display.

      2. A remote IP address serving Remote Display of this VM may be unreachable from a client machine. Please use ping or any other suitable tool to check whether the IP address of VNC server is unreachable. VNC IP and port is provided in the page description. If you find it so, use VM's General Settings/Remote Display controls to choose other IP address for VNC server for the VM, or ask your network administrator to resolve this problem.

        Please note, that if the host server has an internal (non-routeable) IP address, the connection to this IP address can be limited (from the local network or through VPN connection).

      3. VNC applet is not shown on the page or it is 0x0 pixel size: VNC server is a separate application that can fail to start (in case two VMs share one port due to manual settings) or exit with error, in such cases check VM's General Settings/Remote Display settings, resolve the IP/port conflict and restart VM.
    2. Client problems:

      • VNC client is sometimes shown as white rectangle and not responding to user actions: check Java Plug-in Console (browser specific) for errors. Most common problem is 'out of memory' error when viewing large remote screens. To address this problem, provide more memory for Java applets. Follow instructions on section "Java Applet Runtime Settings" and set -Xmx128M in 'Java Runtime Parameters' allowing plugin to use up to 128 Mb.
  3. Console usability issues:

    1. Tab key not working, VNC applet isn't resized to fit window - see the section 1 to ensure that the Java and Java plugin are up-to-date.

    2. Jumpy and offset mouse:

      • check that you are using up-to-date version of Parallels Server;
      • use 'grabbed mouse' mode - to toggle it click on applet or use 'Ctrl-Alt' keystroke.
    3. Can't enter 'Ctrl-Alt-Del', 'Alt-Tab' and such - use 'Toggle Sticky Keys' and enter keystrokes sequentially like: press 'Alt' > release > press 'Ctrl' > release > press 'Del' > release = 'Ctrl-Alt-Del'.
  4. You've updated PVA and expected fixes for VNC applet functionality are not available - please, use instructions from to clean Java applets cache or open Java Console and type xgc and reload page with VNC applet.

  5. After reading 1-4 you have still problems using VNC applet - you may consider using a standalone VNC viewer available at

  6. VM's Remote Display (VNC) server is not available both in a VNC applet and using a standalone viewer.

    1. Check that Remote Display is enabled in VM's General Settings and VM is running.

    2. Consider using alternative solutions:

      • SSH or VNC server running in guest Linux or Unix - like OS bound to VM's IP address;
      • Terminal Server or VNC server running in guest Windows OS bound to VM's IP address.
    3. The only way to connect to VM that has neither VNC server running on host nor remote access services (see 6.2) running in guest OS is to use Parallels Server Management Console GUI.

Search words:

vnc console

remote display

vz: консоль

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