Questions on Prior Releases -- ExtendSim 9 & Older

All ExtendSim versions are upwardly compatible. So ExtendSim 10 will read in models built in ExtendSim 9, 8, and 7. ExtendSim 9 will read in models built in ExtendSim 8, 7, and Extend 6. And so on.

However, ExtendSim is not backwardly compatible. Models and blocks you build in ExtendSim 10 cannot be read by earlier versions, such as ExtendSim 9 or ExtendSim 8. Models and blocks you build in ExtendSim 9 cannot be read by earlier versions, such as ExtendSim 8 or ExtendSim 7.

If your operating system has recently been updated and you are using an ExtendSim release prior to 9.3, Windows may be blocking the launch. With release 1709 (October 2017) Windows changed how the memory manager worked, which caused crashing and hang ups when launching older installations of ExtendSim.

If you are using ExtendSim 9 (released prior to November 16, 2017), 8, or 7, get your fix here.


If you have a Network license and ExtendSim on Client devices no longer launches, the Service (exService) may not be running correctly. In cases where the Server has been restarted, exService sometimes fails to correctly re-communicate with Client devices. The solution is to Stop the Service on the Server, then Start the Service. (Note: A Client license of ExtendSim will remain launchable for several hours after losing communication with the Server’s License Manager. However, if communication is not restored, ExtendSim will not launch. Thus, this issue can occur many hours after the Server has been restarted.)


If you are trying to enter numbers into editable text boxes in a block dialog and nothing appears, the problem could be that your system has been set to use right-to-left text for programs that do not use Unicode. This setting will work for programs that are built to expect to use right-to-left text, but not for programs that are not set to expect this.

You may need to change your system locale. The system locale determines the default character set (letters, symbols, and numbers) and font that you use to enter information and that are used to display information in programs that do not use Unicode. Selecting a different language for the system locale will not affect the language in menus and dialog boxes for Windows or other programs that do use Unicode. Try changing the default locale to English (United States) and check to see if this helps.

To change the system locale, follow the instructions at:

If you receive an error message on your client installation when trying to check a license out of your ExtendSim 9 network license it is probably the result of not having sufficient permissions on your client machine to checkout the license. The checkout process requires some administrative rights on the client machine and many companies are restricting these rights from users.

Try using the right-click command Run as administrator. If this doesn't work, then you may not have been granted sufficient permissions by your company on the machine to check out a license.

exServiceCheck if exService is running as a Service. For Windows, look in Computer Management\Services and Applications\Services.

Task ManagerLook in the Task Manager's Details tab. Both exServer and exService should be listed as running and both should list the System as the User Name. If the User Name for either of them is not System, the License Manager needs to be reinstalled.

When you open and convert a model that was built in ExtendSim 9 to ExtendSim 10, it does not exist as a file on your computer until you explicitly save it. Basically, it is just residing in memory in an intermediate state with no associated file path. Thus, when you try to import a text file using a Data Import Export block, the application does not know where to look for that text file. So, imports will not happen until a model has been saved.

To enable an ExtendSim 9 model that contains Data Import Export blocks that use relative pathname specifications to import and export properly, you must open and convert the model to ExtendSim 10. Then, SAVE it before running it.