Fatal error:Call to undefined function wp_is_mobile

Try:
– switching to the Twenty Eleven theme by renaming your current theme’s folder inside wp-content/themes and adding “-old” to the end of the folder name using FTP or whatever file management application your host provides.

– resetting the plugins folder by FTP or phpMyAdmin.

– re-uploading all files & folders – except the wp-content folder – from a fresh download of WordPress.

– running the upgrade manually via wp-admin/upgrade.php

I have done that, as said above.

I think I have now solved it – I found the tmp file from the upgrade and used that to copy the files over. So now back where it was before upgrade – working!

Thank you for your help anyway.

having same issue on a few sites.

Please post your own topic.

for me the problem plugin was “sitepress-multilingual-cms”… once i changed the name or deleted it up and running again.

Had the same problem: Fatal error: Call to undefined function wp_is_mobile() in D:\Hosting\…

Did ––> re-uploading all files & folders – except the wp-content folder – from a fresh download of WordPress.

Working again now. Thank you esmi

I still do not have a working copy of WordPress ?? It was partly working, but I couldn’t add tags or images without it complaining about missing files. So…

I installed Filezilla. I took a fresh downloaded copy of WordPress 3.4.

I copied the folders wp-admin and wp-includes into my host directory, on top of the old ones that were already there. I also copied the loose files that are in the wordpress main directory – in other words I copied everything except the wp-content folder, as suggested above.

Now when I try to go into wordpress it tells me it needs to update the database. I click the Update Database button and get an error:

Fatal error: Class ‘WP_Theme’ not found in D:\Hosting\9251946\html\tinteddy\wordpressdir\wp-includes\theme.php on line 106

I tried renaming my theme as yoko-old. But this still happens.

I have also renamed the plugins folder plugins.hold, as suggested.

I still get the request to update database, then that error message.

Is there any way to clear it, reinstall and then drop my blog posts back in?

I feel hopelessly out of my depth and just want to be able to use my blog. Nothing technical, just basic posts ??

Delete the wp-admin & wp-includes folder as well as all files in your root folder with the exception of wp-config.php and your .htaccess file (if you have one). Then re-upload all files & folders – except the wp-content folder – from a fresh download of WordPress.

Thank you, esmi, I am doing that now… (nervously)

As long as you stay away from the wp-content folder, you should be fine. I also recommend that people make backup copies of their wp-config.php and root .htaccess files for safekeeping – just in case they get a little carried away with the delete button.

Yay, everything seems to be back to normal in my dashboard now. I see my posts etc. And no error messages.

But my blog is not online. When I go to the address there is nothing at all.

I backed up the whole thing before poking. I don’t seem to have had an .htaccess file. And I copied my old wp-config.php file over so using that.

Oooh, i renamed the theme back to what it was.. and now i see my blog again!

Thank you so much, esmi *hugs you like mad*

Glad I could help ??