Creating window error under Windows XP

This article describes how to modify the registry parameter SharedSection to deal with a frequent problem of window creation.

Applies to :

Octopus under Windows XP

Symptom :

Octopus crashes frequently and the error log indicates an error with window creation. The problem occurs especially on PCs where multiple applications are used simultaneously.

Cause :

The system lacks desktop heap memory.

Solution :

Increase the desktop heap memory size by modifying windows registry.

Procedure :

Note: Increase the desktop heap memory size by modifying windows registry:;EN-US;184802

Warning : This procedure lists the steps to show you how to modify the Registry. However, important problems can occur if you modify the Registry incorrectly. Therefore, make sure you follow these steps attentively. For added protection, back up the Registry before modifying it. Then you will be able to restore the registry if a problem occurs.
  1. Run RegEdit
  2. Find the key HKEY_LOCAL_MACHINE\\System\\CurrentControlSet\\Control\\Session Manager\\SubSystems
  3. Select, on the right-hand side, the "Windows" string (contains a very long value)
  4. Double-click this entry to edit the string
  5. A part of this string contains the value “SharedSection=1024,3072,512”. Replace the second one: (3072) with 8192
  6. Save
  7. Reboot the PC.

If you want more information concerning the error itself or the proposed solution, please do not hesitate to communicate with Octopus technical support.

Other information:

The window creation error can occur frequently on Windows XP depending on the applications you use. When this error occurs, it's because Windows lacks Desktop Heap memory. The desktop heap is memory space used to register information on handles, USER objects and GDI objects allocated. This memory space is also used to load hardware drivers and possibly more information. One of the symptoms of the problem is that many applications start to behave erratically (crashes, corrupted graphical interface). Its symptom in Octopus is the window creation error.

Here are a few references on the Desktop Heap subject.

The theoretical maximum memory size of the desktop heap is 48Mb. This includes all the interactive or non-interactive sessions that may be running simultaneously on a single system. Thus, Windows limits the size it allocates to a single session, so they may all run at the same time without interfering with each other.

Concerning HKEY_LOCAL_MACHINE\\System\\CurrentControlSet\\Control\\Session Manager\\SubSystems 

In the Registry value : SharedSection=1024,3072,512

  • The first value is a common space shared between all desktops
  • The second is the maximum size for the desktop heap of an interactive session
  • The third is the size of the desktop heap in a non-interactive session
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