[Bluej-discuss] Unable to create virtual machine

Michael Kölling mik at mip.sdu.dk
Thu Oct 21 01:26:02 EST 2004

On Oct 19, 2004, at 18:46, Todd O'Bryan wrote:

> My students just started using BlueJ today. Well, they tried to. It 
> runs fine for me as an Administrator, but they keep getting "Unable to 
> create virtual machine" messages that kill the whole program. Since I 
> don't think the TCP/IP settings are different for the two types of 
> accounts, it seems like the FAQ version of the problem is not the 
> problem. (Though I guess it could be. Can somebody tell me how to 
> check? We're not using a firewall.)

Hi Todd,

This one is new to me. We have seen other kinds of problems related to 
not being Administrator on frozen machines, but not the 'create VM' 
problem. So I cannot offer very good advice.

One shimmer of hope is this (if you can wait a few days): we are close 
to releasing the next maintenance version (2.0.2) - probably in two 
days or so. (This includes the fix for printing stack traces that one 
esteemed reader of this list so eloquently requested ;-)

In this next release we have also added an alternative protocol for 
BlueJ's two VM to talk to each other. This protocol does not use 
TCP/IP, and we have done this specifically to avoid these kind of 
problems. (The "Cannot create virtual machine" problem in conjunction 
with various network/firewall configurations is the most common problem 
reported to our technical support.)

If it is indeed the TCP/IP access that is causing your problem, then 
this should provide a solution.

> The machines are fairly locked down so that students can't run 
> programs except in specified directories. Which ones need to be open 
> for BlueJ to work?

BlueJ needs read access to its own installation directory and 
subdirectories, and the JDK installation directory.

On Windows, it needs write access to <user_home> (which I think is 
'Documents and Setting/<username>' or something similar) where it will 
create a directory named 'bluej' to store personal preferences.

It will also try to read the registry to find out which Java version to 
use. If run for the very first time, it will attempt to write the 
selected Java version to the user space in the registry.


Michael Kölling                                       Mærsk Institute
http://www.mip.sdu.dk/~mik             University of Southern Denmark

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