Chinna444

You would want to check if there is any other PHP8 incompatibilities. While you may have upgraded the application, it may still be incompatible so much so, simply having the files on your server is causing an error in that case.
If there are no incompatibilities listed in the ACP. You need to grab the server error log entry from your server for the 500 Internal Server error you’re hitting and we can provide further guidance. 

You are currently in our staffed support forum and receiving support from me, an IPS customer service agent (hi 🙂). This is where you would submit any technical support questions/issues. Your same great support is done here but don’t worry, our staff still have secure access to your details through our client area and if something should require escalated service we can still do that. 

Try here: https://invisioncommunity.com/clients/purchases/

If there is not an upgradable version compatible with PHP 8, you will need to uninstall it or contact the author for assistance. Third party add-ons are outside our scope of support.

You need to upgrade the app to the newest version and then uninstall if you want. You are required to update it otherwise you’ll get the error.

PHP 8 theme issue it seems. Please switch to an unmodified theme and disable all third party applications and plugins then test again. If it works, you’ll want to enable slowly each third party item. 

That warning is taking me to the plugin 3rd party website. I got the new version but i don't see option to upload. 
Generally, as attached in this screenshot it should show the 'Upload new version' option. But, for this outdated version i don't see the option to upload new version.
 

But i am unable to see the upgrade option in the admin panel. For other applications i able to see it.
Also, i am unable to disable it temporarily.