Corona is not showing up as available renderer and is not present on the plugins list!
In such case, please follow the below solutions one by one (try Solution 1; if it doesn't work - try Solution 2; and so on):
Fully update Windows and manually install the additional components NET Framework and MSVC++ Redistributables:
While this step may seem unnecessary, try fully updating Windows as the first thing. This often resolves the problem immediately. Note that you may need to restart your computer, check for updates again, let Windows install an update, restart your computer, and repeat the process a few times until "You're up to date!" message appears in the Windows Update dialog.
Also, manually install the following Windows components:
1) Uninstall all versions of "Microsoft Visual C++ Redistributable" (x64 and x86):
Go to the Windows "Programs" list, then find "Microsoft Visual C++ Redistributable", and uninstall all entries - both (x86) and (x64) ones.
2) Restart your computer
3) Install the newest MSVC++ Redistributables (x64):
Download link: [link]
4) Restart your computer
Download link: [link]
Uninstall Corona Renderer from Windows "Add or remove programs" list. Then install it again using the newest installer from https://corona-renderer.com/download/
In 3ds Max, go to Customize > Configure User and System Paths...
Then go to the "3rd Party Plug-Ins" tab and make sure that the "Additional Max plug-ins" path is set to your 3ds Max installation folder\PlugIns (e.g. C:\Program Files\Autodesk\3ds Max 2021\PlugIns).
If the path is different, modify it and point to the correct path.
If the path is not on the list, add it:
Try the following:
1) Go to the Windows "Add or remove programs" list and make sure Corona Renderer is uninstalled
2) Go to your 3ds Max installation folder (e.g. C:\Program Files\Autodesk\3ds Max 2020) and search for the keyword *coron*
3) Remove all search results - NOTE: to stay safe, it is best to move those files to the trash bin rather than remove them forever. This is in case you need to restore the files.
4) Go to your 3ds Max installation folder (e.g. C:\Program Files\Autodesk\3ds Max 2020) and search for the keyword *legion*
5) Remove all search results - NOTE: to stay safe, it is best to move those files to the trash bin rather than remove them forever. This is in case you need to restore the files.
6) Go to C:\Users\_username_\AppData\Local\ and remove the "CoronaRenderer" folder
7) Go to C:\Program Files and remove the "Corona" folder
After doing that, install Corona again using the "Custom" mode in the installer. On the page where you can select various items, make sure that your 3ds Max version is selected.
If Corona is still not visible on the list after following the above points (which is very unlikely!):
1) Go to your 3ds Max installation folder (e.g. C:\Program Files\Autodesk\3ds Max 2020)
2) Open the "Plugins" folder
3) You should find the following files there: CoronaMax2020.dlr and CoronaMaxUtils2020.dlt
5) Cut those files (Right click > Cut or press Ctrl+X)
6) Go to back to your 3ds Max installation folder
7) Open the "stdplugs" folder (if it does not exist, create this folder manually, the path should be C:\Program Files\Autodesk\3ds Max 2020\stdplugs)
8) Paste the CoronaMax2020.dlr and CoronaMaxUtils2020.dlt files from the "Plugins" folder to the "stdplugs" folder
Start 3ds Max, check if Corona is available and works fine now.
If applying the above solutions step by step did not resolve your issue, the last resort is reinstalling Windows from scratch.
Please contact us if you are still unable to get Corona Renderer running even after trying all of the above steps.