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Support FAQs

How do I uninstall the software?

Open the Help menu and select Registration Information to open the Registration dialog. At the bottom of the dialog, click Deactivate Software. If you use Windows, go to Programs and Features in the Control Panel and use the “Uninstall a program” option to complete the deinstallation. If you use a Mac, drag the software from your Applications folder to the Trash, then empty the Trash.

Why can’t I open a model with an .stm or .itm extension?

Models with .stm or .itm file extensions were built in our older line of software and can’t be opened in Stella Architect or Stella Professional. These models can be converted to the correct file format to be opened in Stella Architect or Stella Professional. You can send these models to and we will convert them for you.

Every time I start the software on my Mac, it prompts me for my registration number. How can I make it stop?

You may have a program that cleans your Mac settings daily. You’ll need to edit its settings to prevent it from cleaning our software.

Can I publish simulations privately?

Yes, isee systems provides several ways to publish simulations privately. Please contact for more information, or see When you publish a simulation to the isee Exchange, is it available to everyone?

Why do I get the message “can’t connect to isee systems license server” when trying to activate my software?

This usually means that your network’s firewall is preventing your computer from sending information to the server that activates your license. In that case, you’ll be prompted to use the Web browser method for installation. (This does not apply to the Lab Pack or Site license.)

Why do my graphics look strange?

Most users find that standard software installation proceeds smoothly. However, certain graphics settings on some computers may occasionally cause issues. As a current fix please do the following:

  • Uninstall the software and reinstall
  • During the setup, select the Custom installation box
  • Upon reaching the screen shown below, select 'Graphical Support' and continue the installation. If problems persist, opt for the 'Alternative Graphics' setting.
How do I install lab packs?

The lab pack installation instructions (downloadable on the My Products page under user’s listed license) describe how users can run the deployment script silently if they so desire.

The Usage Limiter does require internet access in their lab.

Why can't I run STELLA and iThink version 10?

We regret to announce that STELLA and iThink version 10 is no longer supported. To continue using our software, we recommend that you update to either Stella Professional or Stella Architect.

How do I renew my support?

If you are notified that your support is about to or already has expired, please send an email to with your registration number(s) and request a quote. Or you can call us at 603-448-4990 and customer service will help you.

When I enter the registration number for a Lab Pack or site license, why do I get the message “Invalid use of a Lab/Site License Registration Number”?

Lab Packs and site licenses require special installation processes, so their registration numbers can’t be entered directly into the software. Their installation instructions can be found under the registration number for that license in your isee account.

What does the Maintenance and Support Contract include and what are its terms?

The contract includes all software updates and allows you to request software installation assistance, troubleshooting and general “how-to” advice over telephone or email.

Why can’t I see my model’s interface with the isee Player?

The isee Player lets you open and run a Stella model. You can use Stella Live to view results. The interface is not available in the isee Player.

What should I do if I have issues with software features?

If you encounter any problems with our product features, we recommend first referring to our documentation, YouTube channel, webinars, and other available resources to gain a better understanding. If you still experience issues after exploring these resources, please don't hesitate to reach out to our technical support team for assistance.

I have a .stm or .itm file created in iThink or STELLA 1.0-10.0. How can I run it on the current software?

After transitioning from our older generation products to Stella Architect and Stella Professional, the previous file extensions (.stm and .itm) are no longer compatible with Stella products. If you have any files that require translation, kindly submit your request to our Technical Support team at

How can I request a new feature?

We are committed to ongoing product improvement based on user feedback, which plays a crucial role in our development process. If you have an idea that you believe could enhance Stella, please don't hesitate to contact us. However, it's important to note that we receive numerous requests, and we operate with limited resources, which may prevent us from implementing all suggested ideas.

What is covered by Technical Support?

Technical Support is provided by telephone or email and includes software installation support, troubleshooting, and general software "how-to" questions. Our support team is available Monday through Friday, 9:00 am to 5:00 pm ET, except on holidays.

What is NOT covered by Technical Support?
  • Complex modeling questions requiring expertise in system dynamics, agent-based modeling, or discrete event modeling. Our Technical Support team is primarily focused on addressing technical issues related to our software products and assisting users with operational and functionality concerns. While we strive to provide guidance on using our tools effectively, advanced questions are outside the scope of tech support. Our consulting services can assist with these questions.
  • Research-related problems, especially those specific to individual cases or research projects. Our support is not a substitute for domain-specific research consulting. We recommend seeking domain-specific expertise or consulting resources for research-related inquiries that extend beyond the technical aspects of our software.
Where can I find an answer besides contacting Technical Support?
  • Modeling Support Bundle: Our support bundle offers direct assistance building a model. Work directly with an expert for personalized modeling guidance. This eight-hour bundle offers a deep dive into understanding your issue, framing queries in system dynamics, and building your model.
  • Consulting: Consider our consulting services, where our experts can work with you to uncover the structure of your specific challenges and collaboratively explore solutions to improve your outcomes. Consulting services can provide in-depth support for complex modeling and research needs, going beyond what standard technical support can offer.
  • Documentation: Our interactive online documentation holds all the information for beginners to advanced users. Including examples and demo videos, this is a great resource for specific questions.
  • Tutorials: Learn the mechanics of Stella and iThink with our online tutorials. Broken into small manageable videos, the tutorials walk you through the basics of building a model.
  • Webinars: Review our webinars which dive deeper into specific features of our software and present examples.
  • YouTube: We also have many additional presentations and videos that you may find useful on our YouTube channel.
  • Resources for Learning: For newcomers to Systems Thinking and System Dynamics, our Resources for Learning page is the perfect starting point. It includes recommended books, online training, public workshops, and formal training, each tailored to different learning stages and interests.

Looking for software help?

Phone: (603) 448-4990 Email:

   Monday - Friday: 9:00 am - 5:00 pm EDT | Saturday - Sunday: Closed
24 Hanover St, Ste 8A | Lebanon, NH 03766 | US

isee systems inc. holds trademarks registered in the U.S. Patent and Trademark Office for iThink®, Stella®, isee systems® and claims the following trademarks; isee NetSim™, isee Exchange™, Stella Live™, Causal Lens™, Stella Online™, Stella Professional Online™, and Assemblies™.

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