In many cases it is difficult to tell what is going on with the system without looking at log files. It is also often necessary to increase the amount of logging to figure things out. This page lists how to get those log files on different platforms.

Simply add -Log *:stderr:100 to the vncviewer command line and it will output more logging. You can then easily pipe this to a file in order to attach to a bug report:

$ vncviewer -Log *:stderr:100 > tigervnc-viewer.log

You can also specify -Log *:file:100 and you'll get a log as /tmp/vncviewer.log instead.

Note that when you use the -Log command line option, vncviewer will display a semi-transparent debug graph in the lower right corner of the client window. This graph shows connection throughput information including input/output bit rate, pixel throughput rate and so on. This graph is painted atop the content of the client window and may obscure it. You may disable this graph by omitting the -Log option.

Presently there does not seem to be a way to separately enable/disable logging and display of the connection throughput diagnosis graph. This issue provides more information.

There are multiple ways to start the server on Linux, and they will produce a log file in different places.

The log file is stored as ~/.local/state/tigervnc/<host>:<display>.log¹. Extra logging can be enabled by adding the arguments -Log *:stderr:100.

¹ ~/.vnc/<host>:<display>.log if you have an older setup

Logging is sent to stderr so a pipe is needed to store the output. E.g.:

$ Xvnc -Log *:stderr:100 > tigervnc-Xvnc.log

Unfortunately there is currently no way to get logging when started via inetd.

Logging is sent to stderr so a pipe is needed to store the output. E.g.:

$ x0vncserver -Log *:stderr:100 > tigervnc-x0vncserver.log

When started via systemctl (for example on CentOS), logs go to /var/log/messages.

Add the arguments -Log *:file:100 and you'll get a log file as C:\temp\vncviewer.log. Note that you have to create c:\temp before you start the viewer.

Add the arguments -Log *:file:100 and you'll get a log file as C:\temp\WinVNC4.log. Note that you have to create c:\temp before you start the server.

You can also add the arguments -Log *:EventLog:100 and you'll get the log messages in Windows normal Event Viewer.

The easiest way is to redirect logging to the file /tmp/vncviewer.log using:

$ open -a "TigerVNC Viewer 1.7.0" --args -Log *:file:100

If TigerVNC is not installed in Applications then you need to specify the path to the app bundle:

$ open "/some/path/TigerVNC Viewer 1.7.0.app" --args -Log *:file:100