3.9 introduce an updated visual editor (using the latest version of tinyMCE). This has caused a lot of plugins and themes to have issues as they used deprecated code to “tie-in” to the visual editor. So you’ll want to track down which theme or plugin is causing the issue.
To do this, disable all plugins and custom themes. Slowly re-enable them testing them one at a time until the issue appears. Inform the developer of said plugin/theme that was last enabled.
If this doesn’t find or solve your issue, consider doing a manual re-install and follow these steps:
1) First make a backup of your database and files.
2) Delete all the WordPress files off your server except the wp-config.php file and the wp-content/uploads folder (yes, we’re deleting your themes folder and plugins folder with everything in them).
3) Now download the latest version of WordPress, unzip it, and then upload all the files to your server (obviously don’t overwrite wp-config.php or the wp-content/uploads folder).
4) Point your browser at your site. You should have a working default WordPress installation at this point.
5) Now upload your custom theme and enable it. Does everything work? If not, the theme is your problem and you should contact the developer for support.
6) If your custom theme works, it’s time to slowly add in plugins to the mix. Add in and enable plugins one by one. Test your site after enabling a plugin to see if everything works. If any errors show up, note which was the last plugin enabled and contact the plugin developer. Disable that plugin until a fix has been released or you can find a similar plugin that works with your configuration.
At the end of this you’ll hopefully have a stable and working WordPress site.
Thank you for the tips, but I fear if I attempt any of this I’m going to break something or completely delete something important as this is all new to me. Is there a more simpler way of just downgrading WordPress to use the previous one I had? Or re-installing the previous WordPress? I had no issues with it. Or maybe a way to revert back to my backup I made yesterday? However with Backup Buddy I only backed up the files, not the entire site. I think I would rather switch back to previous WordPress than go through all of the hassle as I definitely want to keep my theme 🙂
Is there a more simpler way of just downgrading WordPress to use the previous one I had?
Do you have a pre-upgrade database backup? Were you aware that downgrading would place your site at significant risk of being hacked? Try reading http://blog.sucuri.net/2012/03/wordpress-understanding-its-true-vulnerability.html
How come it would be at risk of getting hacked? I was using the previous version to 3.9 yesterday and had no issues. It’s just the newest 3.9 that is causing all my issues. I’m not referring to going back to a really odd version, just the previous update, which only came out like a month or so ago. I have a Backup Buddy backup, I did it yesterday before upgrading WP. It’s the database and files backup, not a full backup. Is this what you mean?
Is there a way I could just download the previous version to 3.9 and then install it?
There is currently only WordPress 3.9 – there’s no 3.9.1 yet.
Yes you *can* downgrade back to 3.8.3 but it is not really recommended. To do so you would pretty much do the same steps as I outlined previously but instead use WordPress 3.8.3 files. You can download 3.8.3 (and older versions) here: http://ww.wp.xz.cn/download/release-archive/.
Regarding the risks of hacks: once a new version of WordPress is released (minor or major), the WordPress core developers announce what was fixed or updated. This includes security fixes. So older WordPress installations that do not update are not only vulnerable, but the information about these vulnerabilities is now public knowledge.
Try step 2 from the page below. I was having the same trouble and this just worked for me
http://codex.ww.wp.xz.cn/Using_Your_Browser_to_Diagnose_JavaScript_Errors
