Super strange issue here for me today…
My PC has been acting up a bit, and it suddenly reset today.
Upon loading Windows back up, Corona has disappeared from Max 2023. (The only version of max installed)
I’ve re-installed Corona. No luck. Uninstalled, then re-installed, but I still cannot see Corona listed in Max as a render engine.
Any ideas how I can get it back? I’m stumped… (hopefully without a full max re-install, please!)
Thanks!
Strange indeed. Did you try complete Corona uninstall through add/remove programs, including all Chaos services, before installing everything back?
I didn’t remove the chaos stuff… will try that now.
Of course this happens during deadline times 
Will get back to you asap! Thanks!
If nothing will help, i suggest to open a support ticket at Chaos help portal, as this probably would be the fastest way to get qualified help. https://support.chaos.com/hc/en-us/requests/new
Thanks,
Ticket submitted.
Uninstalling all Chaos programs didn’t help… perhaps deleting some temporary files from somewhere might help?
Try cut and paste your ENU folder to the desktop temporarily.
C:\Users*USERNAME*\AppData\Local\Autodesk\3dsMax\2024 - 64bit\ENU
Start 3dsmax, it will recreate the ENU folder. If the problem is fixed then you have a corrupt file in your ENU.
If its not fixed then put your old ENU back so you get all your settings back and then hopefully you will get a response from your ticket.
Thanks James,
That didn’t work unfortunately.
I got a speedy reply to my ticket (thanks Chaos Support!):
I was told I will have to “perform a clean installation of both the 3D platform and Corona due to possibly stuck cache in between them.”
I wanted to avoid it, but I took this chance to upgrade max and so now all is working again now after going thru the painful process of setting up up just how I like…
I think it might also be some corrupted Windows component. It may be worth trying to reinstall NET Framework and MSVC++ - https://support.chaos.com/hc/en-us/articles/4526221582993
(and also check for any pending Windows Updates)
I noticed some windows updates happened yesterday/today… so this may very well be the culprit!
Anyhow, all re-installed again and working. Half a day wasted, now to update all the software on the other PCs … faceplam