VB6 IDE cannot load MSCOMCTL.OCX after update KB 2687323
The problem:
Microsoft Office 2010 products (or later) install updates that break compatibility of MSCOMCTL.ocx and COMCTL32.ocx. Unfortunately this affects many other programs such Visual Basic 6 SP6 and even Oracle Virtual Box v5. The actual problem is HKEY_CLASSES_ROOT\TypeLib\{831FDD16-0C5C-11D2-A9FC-0000F8754DA1}\2.0 registry key. You can find detailed background information about this problem here.
Here is another working solution:
The solution assumes you have not damaged your registry by deleting, replacing and re-registering MSCOMCTL.ocx and COMCTL32.ocx without unregistering the Office patch files.
Create a batch file called fix.cmd and place the following commands in it:
regsvr32 /s /u %windir%\SysWOW64\comctl32.ocx
regsvr32 /s /u %windir%\SysWOW64\mscomctl.ocx
del /y %windir%\SysWOW64\comctl32.ocx
del /y %windir%\SysWOW64\mscomctl.ocx
msiexec /passive /norestart /i KB2708437.msi
msiexec /passive /a KB2708437.msi
regtlib %windir%\SysWOW64\msdatsrc.tlb
Download from Security update for Visual Basic 6.0 Service Pack 6: August 14, 2012 the msi file and rename it to KB2708437.msi.
Note: A direct link to the Service Pack 6 download is located HERE.
Run fix.cmd and the problem will be fixed!
What fix.cmd does is to properly unregister and then delete the current MSCOMCTL.ocx and COMCTL32.ocx files, and then apply the latest Visual Basic 6 SP6 rollup patch. In fact, the script enforces the patch to be installed and then re-installed by updating every file, regardless of version. Finally it registers msdatsrc.tlb type library.
Please let me know if this works for you.
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Advanced Solution:
If however you have accidentally damaged your registry, you need to get as many versions of MSCOMCTL.ocx and COMCTL32.ocx you can find. Then you need to start from the newer version going back to the older and register and unregister the ocx files.
The latest version of MSCOMCTL.ocx is 6.1.98.39 (v2.1) of May 2012 which is more likely the one installed on your system and causing all your problems.
The oldest (legacy) version is that shipped with Visual Basic 6 on 1998 6.1.97.82 (v2.0), or the one shipped with an early service pack 6.1.97.86 on April 2005.
Example:
regsvr32 /s comctl32.6.0.98.34.ocx
regsvr32 /s /u comctl32.6.0.98.34.ocx
regsvr32 /s comctl32.6.0.81.6.ocx
regsvr32 /s /u comctl32.6.0.81.6.ocx
regsvr32 /s comctl32.6.0.81.5.ocx
regsvr32 /s /u comctl32.6.0.81.5.ocx
regsvr32 /s mscomctl.6.1.98.39.(2.1).ocx
regsvr32 /s /u mscomctl.6.1.98.39.(2.1).ocx
regsvr32 /s mscomctl.6.1.98.34.ocx
regsvr32 /s /u mscomctl.6.1.98.34.ocx
regsvr32 /s mscomctl.6.1.97.86.ocx
regsvr32 /s /u mscomctl.6.1.97.86.ocx
regsvr32 /s mscomctl.6.1.97.82.(2.0).ocx
regsvr32 /s /u mscomctl.6.1.97.82.(2.0).ocx
regsvr32 /s /u %windir%\SysWOW64\comctl32.ocx
regsvr32 /s /u %windir%\SysWOW64\mscomctl.ocx
del /q %windir%\SysWOW64\comctl32.ocx
del /q %windir%\SysWOW64\mscomctl.ocx
msiexec /passive /norestart /i KB2708437.msi
msiexec /passive /a KB2708437.msi
regtlib %windir%\SysWOW64\msdatsrc.tlb
WARNING:
Do not search the internet for those files. To find different version of the OCX files download and extract official Microsoft Installer packages such as the following:
2005 Apr - Microsoft KB896559
2008 Dec - Microsoft KB926857
2009 Apr - Microsoft KB957924
2012 May - Microsoft KB2708437
It is also recommended to run CCleaner version 4.0 or later to fix any other ActiveX related problems on your computer.
The problem has been resolved by running the following in elevated command prompt:
command :
cd C:\Windows\System32\
regtlib msdatsrc.tlb
or
cd C:\Windows\SysWOW64\
regtlib msdatsrc.tlb
I hope this helps.
After hours of effort, system restore, register, unregister cycles and a night's sleep I have managed to pinpoint the problem. It turns out that the project file contains the below line:
Object={831FDD16-0C5C-11D2-A9FC-0000F8754DA1}#2.0#0; MSCOMCTL.OCX
The version information "2.0" it seems was the reason of not loading. Changing it to "2.1" in notepad solved the problem:
Object={831FDD16-0C5C-11D2-A9FC-0000F8754DA1}#2.1#0; MSCOMCTL.OCX
So in a similar "OCX could not be loaded" situation one possible way of resolution is to start a new project. Put the control on one of the forms and check the vbp file with notepad to see what version it is expecting.
OR A MUCH EASIER METHOD:
(I have added this section after Bob's valuable comment below)
You can open your VBP project file in Notepad and find the nasty line that is preventing VB6 to upgrade the project automatically to 2.1 and remove it:
NoControlUpgrade=1