From: John Stone (
Date: Thu Feb 06 2020 - 10:28:29 CST

  I believe that the failure you experience with MobaXterm is caused
by it forwarding only one DISPLAY connection at a time (the first one VMD
creates, for the OpenGL display window). I believe that it fails during
Tk startup because Tk creates its own independent display server connection
and that one, for some reason, isn't getting forwarded correctly by MobaXterm.
As a result, Tk fails to initialize its display connection and it raises a
fatal error, and so VMD is forced to terminate. Since you were able to
run "wishx" all by itself, I think this is purely an issue of 1 display
connection vs. 2 connections. I recommend that you proceed using the Xming
tool if it has been successful, until you find a way to resolve the problem
with MobaXterm.

Best regards,
  John Stone

On Thu, Feb 06, 2020 at 02:00:10PM +0900, George Mogami wrote:
> Dear John,
> Thank you for your reply. Your advice was to the point.
> I am using MobaXterm as Xserver with SSH terminal,
> which is useful because X11-forwarding and DISPLAY settings are constructed automatically.
> However, it means we can not know the internal settings except for the DISPLAY environment variable (localhost:10.0).
> Then, I tried to stop Xserver of MobaXterm and start Xming,
> and set the DISPLAY environment variable as (remote PC address),
> and VMD was launched with no error.
> If I ran "wish" (not wishx) using MobaXterm X-forwarding,
> grey small window appeared and % was displayed in prompt with no error.
> Although VMD became available, I wondered why only VMD Tk got failure.
> In addition, using the same MobaXterm X-forwarding environment in another centos machine,
> I confirmed VMD was launched with no error.
> So, I think it's hard to isolate the problem.
> Anyway, since this isn't an issue with VMD itself, my immediate problem was tentatively solved.
> I would appreciate If you could give me a hint concerning the issue.
> Thanks in advance.
> Best regards,
> George
> On 2020/02/06 6:04, John Stone wrote:
> >Hi,
> > This isn't really an issue with VMD itself, but rather the X server
> >and socket tunneling you're using. It seems that there's some sort
> >of problem with the SSH tunnel you're using to forward your
> >X server connection, which is why Tk is complaining about being unable
> >to connect to the display "localhost:10.0".
> >
> >Your VMD seems to have successfully connected to a GLX X11 server
> >back-end that identifies itself as "Software Rasterizer", but things
> >appear to fail after that when Tk begins trying to initialize.
> >
> >Are you wable to run the "wishx" Tk shell on this arrangement without
> >encountering that error?
> >
> >What do you have your DISPLAY environment variable set to prior to
> >launching VMD?
> >
> >Best regards,
> > John Stone
> >
> >
> >On Wed, Feb 05, 2020 at 10:44:13AM +0900, George Mogami wrote:
> >>Dear all,
> >>
> >>I have used VMD installed in centos 6.8 from SSH connected PC.
> >>Some time ago, VMD became not available using X forwarding.
> >>Following is the log of VMD start:
> >>
> >>$ vmd
> >>Info) VMD for LINUXAMD64, version 1.9.2 (December 29, 2014)
> >>Info)
> >>Info) Email questions and bug reports to
> >>Info) Please include this reference in published work using VMD:
> >>Info)    Humphrey, W., Dalke, A. and Schulten, K., `VMD - Visual
> >>Info)    Molecular Dynamics', J. Molec. Graphics 1996, 14.1, 33-38.
> >>Info) -------------------------------------------------------------
> >>Info) Multithreading available, 28 CPUs detected.
> >>Info) Free system memory: 127916MB (99%)
> >>Info) Creating CUDA device pool and initializing hardware...
> >>Info) Detected 1 available CUDA accelerator:
> >>Info) [0] GeForce GT 710      1 SM_3.5 @ 0.95 GHz,  980MB RAM, AE1, ZCP
> >>Warning) Detected X11 'Composite' extension: if incorrect display occurs
> >>Warning) try disabling this X server option.  Most OpenGL drivers
> >>Warning) disable stereoscopic display when 'Composite' is enabled.
> >>Info) OpenGL renderer: Software Rasterizer
> >>Info)   Features: STENCIL MDE MTX NPOT PP PS
> >>Info)   GLSL rendering mode is NOT available.
> >>Info)   Textures: 2-D (16384x16384), 3-D (512x512x512), Multitexture (8)
> >>MobaXterm X11 proxy: unable to connect to forwarded X server: Network error: Software caused connection abort
> >>ERROR) Tk startup error: couldn't connect to display "localhost:10.0"
> >>X I/O error
> >>
> >>If other process such as "xeyes" and "glxgears", I can display them normally.
> >>In text mode, "$ vmd -dispdev text", that works well.
> >>When I login centos workstation directly and startx, I can use VMD normally.
> >>Then, a problem seems to be around X forwarding setting.
> >>I tried uninstall and reinstall VMD or install of another version of VMD(1.9.3) in another directory.
> >>However, the same error occurred as above.
> >>How can I fix the issue?
> >>Thanks in advance.
> >>
> >>Best regards,
> >>George

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