Knowledge Base

Welcome to OPAL-RT’s Knowledge Base

OPAL-RT offers a repository of support information for optimal use of its technology.

Please note that OPAL-RT knowledge base is not fully optimized for mobile platforms.

For optimal experience, use a desktop computer.

Reference Number: AA-02052 // Views: 97 // Created: 2021-11-16 23:22:07 // Last Updated: 2021-11-19 23:32:56
How to set environment variables when switching to older versions (v10.0) of RT-LAB from RT-LAB v11.0+

Sometimes you need to use older versions of RT-LAB (we will take v10.6.5.293 for this example) when you are currently working with versions of RT-LAB v11.0+ (like 2021.3.2), if you are either working with old projects or old QNX OS/Wanda Systems. 


If you try and run directly the RTLAB v10.6.5.293 (already installed) application (the process to open older versions is to run C:\OPAL-RT\RT-LAB\v10.6.5.293\common\bin\Metacontroller.exe, after which a metacontroller icon will appear in the taskbar, right click on the icon and click on "RT-LAB" to start.)  after just using RTLAB v11.0+ , you will have issues due to the setting of environment variables, some of the errors you can receive are:

"API version does not match RT-LAB version



java.vendor=Sun Microsystems Inc.

BootLoader constants: OS=win32, ARCH=x86, WS=win32, NL=en_US

Command-line arguments:  -os win32 -ws win32 -arch x86 -data @noDefault

!ENTRY org.eclipse.osgi 4 0 2021-11-16 17:47:19.057

!MESSAGE An error occurred while automatically activating bundle com.opalrt.rtlab.api (5)."

"The RTLAB ENVT VARIABLE points to v2021.3 while you are trying to run v10.6.4.280"

This issue does not affect the newer versions of RT-LAB because the environment variables are automatically set. However, for older versions, we have to manually reset and set the Environment variables.

1) There is a convenient way for resetting the environment variables, this features is present in RT-LAB versions upto v2020.2 (Removed in v2020.3) known as "reconfigure for 10.x"  (

2) Next step involves setting the environment variables in the system variables window of the environment variables:
Variable                   Value

Path                          C:\OPAL-RT\RT-LAB\v10.6.5.293\common\bin

PYTHONPATH         C:\OPAL-RT\RT-LAB\v10.6.5.293\python; C:\OPAL-RT\RT-LAB\v10.6.5.293\common\python

RTLAB_ROOT          C:\OPAL-RT\RT-LAB\v10.6.5.293\

RTSB                        C:\OPAL-RT\RT-LAB\v10.6.5.293\Systembuild

3) If you do not have a version that has "reconfigure for 10.x" , you can just the screenshots below for reference and manually remove the environment variable entries for v11.0+ (the environment variables are automatically when you open the v11.0+ RT-LAB versions again, do not worry about losing the data):
When using v11+

When modifying to use for v10.0+