This page contains instructions on debugging the VBoxSVC (server) and Qt GUI frontend activities. In particular, these instructions enable logging of COM components of the so-called VirtualBox Main API. This logging may be helpful when debugging general application problems such as VirtualBox startup errors, VM Selector GUI crashes and so on. For general information about VirtualBox logging, see VBoxLogging.

A debug build of VirtualBox is required for the debug logging. Once you've got the debug build, make sure there are no running instances of the VBoxSVC process and any VirtualBox frontends. Then, set the environment variables as shown below if you are on a Linux host:

export VBOX_LOG=main.e.l.f+gui.e.l.f
export VBOX_LOG_FLAGS="time tid thread"
export VBOX_LOG_DEST=dir=/path/to/all/logs

or as shown below if you are on a Windows host:

set VBOX_LOG=main.e.l.f+gui.e.l.f
set VBOX_LOG_FLAGS=time tid thread
set VBOX_LOG_DEST=dir=D:\path\to\all\logs

Now you may start any VirtualBox client from the given environment and it will log into the specified directory. Note that the VBoxSVC process and all processes it starts will inherit the environment of the first client including the debug variables.