I've installed the Molecular Script add-on on a 64 bit PC running Win7. I do not have admin rights on the PC. I made sure to use the latest 64-bit version of the add-on and I am using Blender 2.77. The file cmolcore.pyd is located inside the "Molecular"-folder here: C:\Users\mwl\AppData\Roaming\Blender Foundation\Blender\2.77\scripts\addons\molecular

When I click the "Start Molecular Simulation" I get the following error: File"C:\Users\mwl\AppData\Roaming\Blender Foundation\Blender\2.77\Scripts\addons\molecular_init_.py",line600,in execute mol_report=cmolcore.init(mol_exportdata) NameError:name'cmolcore' is not defined.

I do not have Microsoft Visual C++ installed on this PC

Any ideas what could be wrong?

The same add-on runs problem free on my 64-bit home PC which runs Win10, and of which I am the administrator.

Kind regards


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Hi again aliasguru I posted an image of the location and version of my add-on. I'm afraid everything looks as it should :-(

  • 1
    $\begingroup$ There's something off with your installation. Maybe you had an older version of the addon installed, and it hasn't been removed yet. The 1.03 version which is compatible with Blender 2.77 should be located at C:\Users\mwl\AppData\Roaming\Blender Foundation\Blender\2.77\Scripts\addons\molecular\ init.py (note that there is a subfolder called molecular. The error you posted indicates the file is in the addons directory. In the same folder molecular you MUST have a file called cmolcore.pyd. $\endgroup$
    – aliasguru
    Jan 17, 2017 at 9:44
  • $\begingroup$ Hi aliasguru Thanks for your quick reply. I did in fact install an older version of the add-on and later deleted it. $\endgroup$
    – Ryosei
    Jan 17, 2017 at 11:42
  • $\begingroup$ Hi again aliasguru Hi aliasguru Thanks for your quick reply. I did in fact install an older version of the add-on and later deleted it. Inside the "Molecular" folder I have one folder called "pycache" and two files: "init.py" and "cmolcore.pyd" I added a screendump of the "Molecular" folder contents above. $\endgroup$
    – Ryosei
    Jan 17, 2017 at 11:53
  • $\begingroup$ hmmm the files should be allright, there is still a source of complication though: in Blender it is possible to have the same addon in multiple folders. Please open your UserPreferences, go to Add-ons, look for molecular, and check a) which version it reports (should be 1.0.3) and b) which installation folder is printed under File $\endgroup$
    – aliasguru
    Jan 17, 2017 at 13:18
  • $\begingroup$ Hi aliasguru I've posted the info you asked for. I guess it's bad news that everything looks as it should. Do you think the reason could be that I also run Blender 2.78 portable from a USB stick on the same PC? $\endgroup$
    – Ryosei
    Jan 18, 2017 at 7:00

1 Answer 1


I found the solution.

It turned out that I did not read PyroEvils instructions before installing the add-on. I did have Microsoft Visual C++ 2013 Redistributable installed. But in order to for the Molecular add-on 1.03 to run you need Microsoft Visual C++ 2015 Redistributable. I got ITServicedesk to install the 2015-version and now the Molecular add-on runs as it should.

I made sure to make a donation to Jean-Francois.


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