I have this warning coming up everytime i try to troubleshoot the 3.9 issue

That error is cause dby one (or more) plugins on your site being incompatible with the upgrade. The wya to debug it properly is to disable all (yes all) plugins and re-enable them one-by-one testing after each one so that you can see which one is causing the problem. When you find that you can leave that disabled, or contact the plugins author to get support on the problem.

I have deleted all of the plugins and it still has not worked. I am not sure what to do do solve this problem.

That sounds very strange. That line is trying to get the plugin paths, so if there’s no plugins, there should be no plugin to register to call that code.

My only suggestion would be to try and re-install 3.9 as it just looks like something hasn’t worked exactly right in the update. If it was me, I’d do it manually via FTP so I could be sure that everything is correct

I tried to go the FTP route I downloaded Filezilla but I dont now how to get it on the site.

You’ll need to get the FTP details from your hosting company. They normally send them out when you first join, so see if you have anything. If not contact their support staff and ask.

FTP download worked i recommend trying this if you have any issues with your update. Thanks everyone!