Have you tried the basic troubleshooting steps to find out where the issue might be coming from?
1) First disable all plugins and custom themes. Use a default theme like twentythirteen. Don’t worry, this is only temporary.
2) Does everything work? Great. Your WordPress installation is fine. Now we’ll check to see if you custom theme is okay.
3) Enable your custom theme – does everything work? If yes, great. If not, make a not of the issue and contact the theme developer for support.
4) If everything has worked up to this point, it’s now time to test plugins. Enable a plugin, one at a time, and then test. If everything is good, move to enabling the next plugin. If the issue appears, note which plugin you last enabled and contact the plugin developer. Tell them which theme and plugins were being used when the issue appeared.
By this process we can figure out more exactly where the issue may be coming from.
I know this is a problem with my theme being incompatible with 4.0, however i can’t make any changes because when I login to my dashboard all i get is a page with the error and nothing else… thank you so much for the help!
I just don’t know how to resolve the error… i’ve messaged the person who made the theme but would it be easier to downgrade back to 3.9? that’s what I’m currently working on…
Okay to disable your theme, use FTP or your server’s control panel to rename the offending theme’s folder. This will disable it in WordPress (which will fall back to a default theme).
Okay done that… error has gone. what would be the next best step? email the person who made the theme?
Yep – contact the theme developer. And provide details about your setup – what kind of server, version of PHP/MySQL, WordPress version, and any plugins being used.
This will help the developer to recreate the issue so they can figure out what they need to fix in their code.
