vncviewer keeps dying, silently

[Mario Nigrovic]

Folks -

Recently, it seems my vncviewer v1.15.0 running on Windows 11  keeps exiting randomly. It's only once or twice per day, so not super inconvenient, but this is new behavior within the last few weeks.

What really concerns me is that I can't find any reason why it's dying, and I can't figure out where to even look. Furthermore, it seems that it doesn't even report diagnostic messages when the command line is incorrect. I'm guessing this is some kind of Windows-specific behavior, so I'm hoping I can get some advice as to how to proceed. I have tried various combinations of the Log option, but I never get any output that I have been able to find.

Thanks in advance for any insights or help offered!

-- Mario Nigrovic

[Pierre Ossman]

On 01/03/2026 22:27, 'Mario Nigrovic' via TigerVNC User

It might be something on the network that kills connections after a
certain time.

To debug this, I would suggest getting a debug log from the client. You
can find instructions here:

https://github.com/TigerVNC/tigervnc/wiki/Debug-Logs#client-1

Regards,
--
Pierre Ossman Software Development
Cendio AB https://cendio.com
Teknikringen 8 https://twitter.com/ThinLinc
583 30 Linköping https://facebook.com/ThinLinc
Phone: +46-13-214600

A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

[Mario Nigrovic]

Thanks. I swear I had tried the logging, before, and gotten nothing! But now it seems to be working for me.

-- Mario

480-753-2373

[Mario Nigrovic]

Folks -

So, not sure what I should be looking for in the log, but here's the tail end of a log file from a vncviewer invocation that just exited:

Mon Mar 02 21:56:26 2026
 CConnection: Key pressed: 22 => 0x16 / XK_U (0x0055)
 CConnection: Key pressed: 25 => 0x19 / XK_P (0x0050)
 CConnection: Key released: 38 => 0x26 / XK_L (0x004c)
 CConnection: Key released: 22 => 0x16 / XK_U (0x0055)
 CConnection: Key released: 25 => 0x19 / XK_P (0x0050)
 CConnection: Key released: 42 => 0x2a / XK_Shift_L (0xffe1)
 CConnection: Unexpected release of key code 42
 CConnection: Key pressed: 15 => 0x0f / XK_Tab (0xff09)
 CConnection: Key released: 15 => 0x0f / XK_Tab (0xff09)
 CConnection: Key pressed: 28 => 0x1c / XK_Return (0xff0d)

Mon Mar 02 21:56:27 2026
 CConnection: Key released: 28 => 0x1c / XK_Return (0xff0d)
 CConnection: Key pressed: 54 => 0x36 / XK_Shift_R (0xffe2)

Mon Mar 02 21:56:28 2026
 CConnection: Key pressed: 39 => 0x27 / XK_colon (0x003a)
 CConnection: Key released: 54 => 0x36 / XK_Shift_R (0xffe2)
 CConnection: Unexpected release of key code 54
 CConnection: Key released: 39 => 0x27 / XK_colon (0x003a)

Mon Mar 02 21:56:29 2026
 CConnection: Key pressed: 14 => 0x0e / XK_BackSpace (0xff08)
 CConnection: Key released: 14 => 0x0e / XK_BackSpace (0xff08)
 CConnection: Key pressed: 14 => 0x0e / XK_BackSpace (0xff08)

This really doesn't look helpful to me, but I guess I'm not sure what I should be looking for?

-- Mario Nigrovic

[Pierre Ossman]

On 03/03/2026 06:02, 'Mario Nigrovic' via TigerVNC User
Discussion/Support wrote:
> Folks -
>

> So, not sure what I should be looking for in the log, but here's the tail
> end of a log file from a vncviewer invocation that just exited:
>

> ...

>
> Mon Mar 02 21:56:29 2026
> CConnection: Key pressed: 14 => 0x0e / XK_BackSpace (0xff08)
> CConnection: Key released: 14 => 0x0e / XK_BackSpace (0xff08)
> CConnection: Key pressed: 14 => 0x0e / XK_BackSpace (0xff08)
>
> This really doesn't look helpful to me, but I guess I'm not sure what I
> should be looking for?
>

If those are the last lines of the log, then it looks like the viewer is
crashing. There should be more log lines stating the reason things
disconnected.

To confirm this, I would suggest installing Dr MinGW. With that
installed, you should get a popup when the viewer crashes with technical
details about what is happening.

Regards,
--
Pierre Ossman Software Development

Cendio AB http://cendio.com
Teknikringen 8 http://twitter.com/ThinLinc
583 30 Linköping http://facebook.com/ThinLinc