Fatal error: Call to undefined function wp_get_theme()

Update WordPress to the latest version and this should be fixed.

Can you confirm?

@davidwells, I ran into the same problem and tried updating the WordPress. But when I click update it tried to update but still showing the same error and the message to update WordPress.

You are on wordpress 3.6?

I was on 3.2.2
Anyway, I just fixed the problem by deleting the theme folder via ftp that was installed last time.

Yeah you need 3.5+ to run landing pages I believe

I am getting this error message (pasted below) when i try to get into my website I tried adding a landing page and now i cannot even get into my dashboard to remove the landing page… PLEASE HELP!

Warning: file_get_contents(/home3/ourbiz/public_html/wp-content/uploads/landingpage-templates/None/index.html) [function.file-get-contents]: failed to open stream: No such file or directory in /home3/ourbiz/public_html/wp-content/plugins/html-landing-page/lp.php on line 105

Warning: DOMDocument::loadHTML() [domdocument.loadhtml]: Empty string supplied as input in /home3/ourbiz/public_html/wp-content/plugins/html-landing-page/lp.php on line 106

Fatal error: Call to a member function saveXML() on a non-object in /home3/ourbiz/public_html/wp-content/plugins/html-landing-page/lp.php on line 143

To fix this immediately follow these steps: https://www.inboundnow.com/what-to-do-if-a-wordpress-plugin-breaks-your-site/

These appear to be warning errors from another plugin however:
/home3/ourbiz/public_html/wp-content/plugins/html-landing-page/lp.php is not our code.

Turn off your “html-landing-page” and you should be fine

Hi

I had the same error and i solved it:

1.- Rename the theme using FTP: /home/wp-content/themes

2.- Upgrade WordPress to 3.8 version

3.- Activate the theme

For me runs perfectly. Thanks!