Fatal error: Call to undefined function wp() in ../wp-blog-header.php?

Fatal error: Call to undefined function wp() in /home/content/33/7211533/html/someSite/wp-blog-header.php on line 14

Can anyone figure whats the problem?

I already update the wp-includes and wp-admin folder and my functions.php is fine, but I haven’t figure out how to fix it. Any suggestions?

EDIT

I reinstalled WordPress, (upload the new copy on the site, and I made sure it’s up to date) – equivalent to a manual update.

After that its started to work fine, so this problem is now fixed.

wp() is quite essential function. It resides in functions.php file (don’t confuse with functions.php in theme, different thing) and I don’t think you can load WP without passing require directive for that file at some point.

So your install seems very broken – either functions.php file in core is damaged or something else is broken and makes it skip loading that file.