Fatal error: Call to undefined function wp_initial_constants() in /home/site/public_html/wp-settings.php on line 26

Question

While updating WordPress 3.6.1 on my site I am getting the following error and the site crashes. Why is this happening to my site, and how can I overcome this problem?

Following error arises:

Fatal error: Call to undefined function wp_initial_constants() in /home/adventec/public_html/wp-settings.php on line 26

Answer 1

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

Make sure that you delete the old copies of files & folder before uploading the new ones.

Answer 2

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.