This project has moved and is read-only. For the latest updates, please go here.

interactive window failed to launch REPL process

Jul 15, 2011 at 9:05 AM
Edited Jul 15, 2011 at 10:11 AM

I have the following config installed:

WindowsXP SP3

VS2010 Pro SP1


IronPython 2.7

works fine (but does not show variables in Watch), Interactive window ok

Disabled in IronPython 2.7: IronPython tools

Installed: IronPython Tools RC1

tools/pref in VS all set to IronPython 2.7

running a Python program via F5 works ok

Starting the Interactive Window results in:

Failed to launch REPL process

Traceback: File ..../ line 7 in <module> .../ Import Error: cannot import name format_exc


My question is of course: how to resolve this?

Remark: same config in Win7 works fine



Jul 15, 2011 at 4:53 PM

What happens when you open an IronPython prompt and type "import threading"?

Jul 15, 2011 at 8:14 PM

import threading in ipy.exe gives exactly the same result.

kind regards,

Jul 15, 2011 at 8:51 PM

This looks like an IronPython issue to me, then. What version of the CLR do you have on your XP box? What version is on your Win7 box? You can find out by looking at what ipy.exe prints when you start it; I get the following in my Win7 box:

IronPython 2.7 ( on .NET 4.0.30319.235
Type "help", "copyright", "credits" or "license" for more information.



Jul 15, 2011 at 8:58 PM
Edited Jul 15, 2011 at 9:06 PM

Both system report .net 4.0.30319.235.

I'll try to reinstall IronPython on the XP box and see what happens.

Alas: same problem.

Jul 16, 2011 at 12:25 AM

I have now tried on an IronPython installation on a fresh XP SP3 and it worked; maybe dinov has some ideas about what could be going on?

IronPython 2.7 ( on .NET 4.0.30319.1
Type "help", "copyright", "credits" or "license" for more information.
>>> import threading
Jul 20, 2011 at 5:23 PM

It seems like you have a broken  If you do this from the ipy.exe what do you get:

import traceback



The path should be something like "C:\\Program Files (x86)\\IronPython 2.7\\Lib\\".  Also, if you open the file outputted by traceback.__file__ does it have a format_exc method?

Jul 20, 2011 at 8:58 PM

Hi dinov,

Thanks for your e-mail. You’ve hit the mark: traceback appeared to be coming from c:\common files\python\python21\lib, which for some reason was in the IRONPYTHONPATH. Corrected that and it works fine now!


Kind regards,

Bob Koeman