Updating from nexus version crash on start

Hi everyone thanks for the help. I updated from the nexus version to the 2020 version on this site. I crash on the oblivion screen starting the game, but when I revert to the nexus version everything works perfectly. Does anybody have any guesses as to why/suggestions?
Thank You

Simply you didnt upgrade correctly. You must overwrite the files with new ones. If you are using a mod installer, that is the problem. You must install OR manually.

I hate to post contradictory information, but I prefer to install OR with Wrye Bash. Like Alenet said, you did not uninstall your old version of OR properly before installing the new version. If you were to use Bash, this wouldn't be a problem (other than INI tweaks, in which case the INIs would be left behind. This could be changed by updating your archives after changing settings). I've never tried any of these managers that use virtual directories, just to point out.

But, to solve your crash, completely uninstall the old version of OR prior to installing the new version.