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The environment variable method set by a Batch command only works for the current session. This means that:

  • It cannot be used to change the Corona version used in the currently running 3ds Max instance.
  • It allows you to have multiple sessions of the same or different 3ds Max versions running with the same or different Corona versions at the same time. 
  • If you start 3ds Max normally without the multiloaders (e.g. using the desktop shortcut), it will be using the version of Corona currently installed in your system - the one installed using the universal installer. 
  • It is safe to change the environment variable while 3ds Max is running. 

It is also possible to set the environment variable permanently using the options available in Windows:

Open the Start Menu and type "environment", then select "Edit the system environment variables". You can add new environment variables there. 

To revert to the version which is currently installed using the universal installer, unset the custom environment variable (if it was set permanently), or just launch 3ds Max normally (if it was set for the current session only). 

Additional Considerations


Step 1: Install Corona 

Download and install the newest version of Corona using the standard installation method in our universal installer. If, for any reason, you wish to install an older version, it has to be at least Corona Renderer 6(the oldest supported version is 31.01.2020 daily build).

Step 2: Download and unpack the other Corona version(s) you would like to use

Download the additional versions of Corona you would like to use. They can be stable versions or daily builds. The oldest supported version is Corona Renderer 5.

Use the "Unpack files" option in the installers of each of the additional Corona versions you would like to use. Unpack the plugin files into any desired folders.

See: How to install Corona Renderer manually using the "unpack files" option?

Step 3: Set up the environment variable

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You can either:

  • Manually add an environment variable in Windows - this works permanently unless you remove or change the variable
  • Use a batch script to automate the variable setting process for you - this is not permanent and works only for the current 3ds Max session

The exact steps for using both methods are explained in this article.

The name of the variable is:

Code Block

Set the variable to the sub-directory where CoronaMax_Release-<YEAR>.dll file is located after the unpacking.

For example, for Corona Renderer for 3ds Max 2019 and "C:\Corona Renderer" as your unpacking directory, set:

Code Block


Code Block
C:\Corona Renderer\Corona\Corona Renderer for 3ds Max\2019

The environment variable tells the "dispatchers" which of the actual Corona plugins to load.

Here is an example Batch command which does that and starts 3ds Max: 

Code Block
SET "CORONA_3DSMAX_2019_LOAD_PATH=C:\Corona Renderer\Corona\Corona Renderer for 3ds Max\2019" & START "" "%ProgramFiles%\Autodesk\3ds Max 2019\3dsmax.exe"

You can simply save this line as a batch script, run it, and it will start 3ds Max 2019 with the Corona version unpacked to C:\Corona Renderer\Corona\Corona Renderer for 3ds Max\2019. Feel free to edit the script according to your needs, for example by changing the 3ds Max and Corona installation paths or the 3ds Max version. 

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When using different versions of 3ds Max and Corona, keep in mind that: 

  • Opening scene files saved with a newer version of Corona using an older version of Corona is not supported and the file either does not open at all, or opens with various issues (such as some features not working, incorrect parameter values, etc).
  • It is not possible to open scene files saved with a newer version of 3ds Max using an older version of 3ds Max. The solution is to re-save the scene in an older 3ds Max format using the 3ds Max File > Save as dialog.
  • Opening scene files saved with an older version of Corona using a newer version of Corona is fine. We sometimes enable legacy switches to keep rendering the same between different Corona versions, so if you would like to try new features, you may need to enable them manually in the newer version.
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Once the environment path is set permanently using the "Edit the system environment variables", it affects the UI version of 3ds Max as well as command-line rendering. This means that the specified Corona version will be used by 3dsmaxcmd.exe, Autodesk Backburner, and in any other case where the rendering is done without the user interface. 

Using Multiloaders with Chaos Scatter