call_user_func_array () error after updating to wordpress 3.6

Hi, the solution is not to edit the core files.

First I’d restore your edit to plugin.php.

Then I’d disable your plugins. Most likely one of them is causing this problem.
After that enable one by one to find the one that is causing the problem.

I have deactivated all the plugins… But the error is still there. Worst part is that I can’t reactivate them now… When I try to reactivate a plugin, I get the following error…

Warning: call_user_func_array() expects parameter 1 to be a valid callback, function '_canonical_charset' not found or invalid function name in /home/mananato/public_html/wp-includes/plugin.php on line 173

Warning: Cannot modify header information - headers already sent by (output started at /home/mananato/public_html/wp-includes/plugin.php:173) in /home/mananato/public_html/wp-content/plugins/w3-total-cache/lib/W3/Referrer.php on line 35

Warning: call_user_func_array() expects parameter 1 to be a valid callback, function '_canonical_charset' not found or invalid function name in /home/mananato/public_html/wp-includes/plugin.php on line 173

Warning: Cannot modify header information - headers already sent by (output started at /home/mananato/public_html/wp-includes/plugin.php:173) in /home/mananato/public_html/wp-includes/pluggable.php on line 875

My website is in a really really bad shape now… Plz someone help

Update:
I reverted back to 3.5.2 and everything is working fine now…

The next question that comes in my mind is that “Is update from 3.5.2 to 3.6 a major update” i.e. Is it absolutely necessary that I do this update…??

i.e. Is it absolutely necessary that I do this update…??

Absolutely!! Every WordPress update is a critical one. WordPress is a very popular open source system. Which, in turn, is a popular target for hackers.

By using an old version of WordPress, you run a very serious risk of attack. Just Google “WordPress Attacks” and you should be more than convinced!

But for me to update to 3.6, I first need to get rid of this error… Or at least know what could be possibly causing it so that i can work on it to find the solutions…..

But so far, I haven’t had any thoughts on what is causing this error

I would disable all plugins (just (afetr backing up) delete all the plugins so that the plugin folder is empty.

After that activate the default WordPress theme.

Then upgrade WordPress to 3.6.

I tried disabling the plugins (not exactly as you described it) but it didn’t work for me.

And I cannot change the theme because I has some extensive modifications suited to my website.

And I cannot change the theme because I has some extensive modifications suited to my website.

Then, unfortunately, there is not much you can do.

This is why all site modifications should be done using a Child Theme.

I would suggest first moving all of your modifications out of core files.. and placing them inside a child theme.

Or you could make a back up of your current theme, delete it and replace it with the default wordpress theme.

Like Josh said: Otherwise there’s not much we can do.

I am only interested in keeping the styles and other modifications of the current theme I am using.
If such a thing is possible using a child theme, then certainly I can go for it.

So I would ask a simple noob question: Is it possible that I adapt the “child theme” thing and the look and feel of my website doesn’t change at all. ?

In theory, you can move your changes to a child theme, yes. First, make a backup copy of your theme folder in a safe place – do not touch it. Then set up the child theme. Any .php files you’ve changed (except functions.php) – put a copy of those in the child theme folder. For style.css – compare your version to an unmodified version and put the changes in the child theme style.css file. For the functions.php file, it depends on what you’ve changed.

What theme are you using? Doesn’t look very current or typical. Also, not all themes will work with a child theme.