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Error using OM in LispWorks on Windows

Hi, I have a problem using OM in LispWorks. I’m on Windows.
I could install everything and I also could start OM through LispWorks with the build-om.lisp file. I can even open a patch. But when I try working in my patch, like doing anything, I get this error message.

Invoking a method “representations” on a null pointer.
(abort) Return to Cocoa Event Loop

I searched for a solution, but I can’t find any. And I don’t understand what this error message means. Does anyone have an idea?
I’m glad about every help.

Hi Tim,

Can you tell what LW version you are using (personal, professonal, 32bit, 64bit)?

More, can you send the error log file?


Hi K,

thank you for your reply. A few things though. I’m trying to solve an error for a student. I wrongly assumed he has windows, but he is on macOS 11.6
with LispWorks Personal 7.1.2 (64-bit)

Here is a picture of how it looks like, every time he tries to open a patch or do something in a patch:

Thank you for your help,

Hi Tim,

This is very strange. What kind of patch you are loading. Can you send it so i can check?
By the way, does this happens when you use an already compiled image such as the latest release (OM 6.19) downloadable here:



Hi K,
yes it’s very strange. It’s just a new empty patch. But with other already coded patches it’s the same. So it seams that it’s unrelated to what patch it is.

It doesn’t happen with already compiled images. It’s only when starting OM in LispWorks with this build-om.lisp file.

Best, Tim

Is it the build-om.lisp already in the distribution from the git or is it a custom one. If yes can you attach it please?


It is the one from git, but we made a small change in these lines, because we don’t need every package. So we commented out some lines, now it looks like this:

(load-om-projects '("basicproject" "musicproject"))
(load-om-projects '("midi"))
;(load-om-projects '("sdif"))
;(load-om-projects '("mathtools"))
;(load-om-projects '("omsounds"))
;(load-om-projects '("space"))
;(load-om-projects '("harmonicproject"))
;(load-om-projects '("sheet"))

So as you can see, we just put the semicolon in front of six of these lines.

But I remember we also made changes in another file in order to get it to work for most of the students. Here is the path to the file and the file name at the end:


Here are the lines we commented out in this file:

          ((scoreeditor-p object)
           (om-set-bg-color (panel (editor win)) *score-bg-color*))
          ;((sound-p object)
           ;(om-set-bg-color (panel (editor win)) *sound-bg-color*))
          ;((or (3dc-p object) (3dc-lib-p object)) t)  
          ((or (bpf-p object) (bpflib-p object))
           (om-set-bg-color (panel (editor win)) *bpf-bg-color*))
          ((maquette-p object) t)
         ;  (progn (print (maq-color (params object))) 
         ;  (om-set-bg-color (panel (editor win)) *maq-color*)))
           ((typep object 'ompatch)
            (om-set-bg-color (panel (editor win)) *patch-bg-color*))
          (t ))

Three lines are commented out. Two including the “sound-p” function and one line including the “3dc-p” function. The problem here was, that we got an error saying these functions are undefined. So that’s what we changed here. But anyway, it seams that this is also not the problem here, because as I said like this it works for all the students except one. So I guess the problem must be somewhere else. But that’s all we changed.

I’m sorry for the late reply,

Ok ,

I can see better now the situation but it is hard to tell from remote, why it is not working with just one installation. It could be related to many factors, encoding, independent cl-packages, typo errors, etc.

Just curious, why did you remove all other projects from OM ?