in wordpress, a valid callback for cp_admin_init and _canonical_charset - callback

Question

I'm using WordPress 3.5 with child-theme of Twenty Eleven 1.5. Suddenly I'm getting following Warning,
Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, 'cp_admin_init' was given in /home/templ/public_html/wp-includes/plugin.php on line 406
Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, '_canonical_charset' was given in /home/templ/public_html/wp-includes/plugin.php on line 173
I'm using following plugins:
download-manager 2.3.9
wordpress-seo 1.4.7
wp-pagenavi 2.83
Some more points:
1) If I'm giving mysite.com it's giving above 2 line warning. If I give www.mysite.com, the following line also include,
Warning: Cannot modify header information - headers already sent by (output started at /home/templ/public_html/wp-includes/plugin.php:406) in /home/templ/public_html/wp-includes/pluggable.php on line 876
2) If I give mysite.com/wp-admin/ or www.mysite.com/wp-admin/, It's giving 1st warning and 3rd warning.
3) If I goto www.mysite.com/wp-login.php, It's giving following 5 warning.
Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, 'cp_admin_init' was given in /home/templ/public_html/wp-includes/plugin.php on line 406
Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, '_canonical_charset' was given in /home/templ/public_html/wp-includes/plugin.php on line 173
Warning: Cannot modify header information - headers already sent by (output started at /home/templ/public_html/wp-includes/plugin.php:406) in /home/templ/public_html/wp-login.php on line 368
Warning: Cannot modify header information - headers already sent by (output started at /home/templ/public_html/wp-includes/plugin.php:406) in /home/templ/public_html/wp-login.php on line 380
Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, 'wp_authenticate_spam_check' was given in /home/templ/public_html/wp-includes/plugin.php on line 173
4) If I give correct username and password, it's not going to login. giving following problem,
ERROR: Invalid username or incorrect password.
ERROR: Cookies are blocked or not supported by your browser. You must enable cookies to use WordPress.
I'm trying to find solution. I can't. Can any-one help me?

Answer 1

This sounds like a corrupted install. So you have a few options to fix this:
Attempt to get logins operational again and doing an upgrade though the wp-admin: Explained Below.
Do a manual Update: http://codex.wordpress.org/Updating_WordPress#Manual_Update
But First: Make a Backup
Please be sure to backup your install! Before proceeding: http://codex.wordpress.org/WordPress_Backups
Getting Logins Working: Masking the symptoms
First I would disable debugging output because that should fix most of these issues. When a warning occurs in Wordpress, PHP starts writing the response body and closes the header section of the response. This means that whenever Wordpress tries to add another header after the original warning was raised, PHP will raise another warning:
Warning: Cannot modify header information - headers already sent by (output started at /home/templ/public_html/wp-includes/plugin.php:406) in /home/templ/public_html/wp-login.php on line 380
So if we disable debugging then we should be able to mask the symptoms. This is a quick patch for a larger problem that we will have to solve with an in-place upgrade
To Disable Debugging
Ensure that the following constants exist and are set correctly is in your wp-config.php file
define('WP_DEBUG', false);
and
define('WP_DEBUG_DISPLAY', false);
Now you should be able to login to your site as an administrator without errors.
Disable your Plugins
Disable all your plugins in Plugins -> Installed Plugins This is imperative so that we can make sure that the update goes smoothly.
Do an Update
Go to Dashboard -> Updates and click either Update Now or Re-install Now
Reactivate your Plugins
Reactivate all your plugins in Plugins -> Installed Plugins and update them if necessary.
That's It
That's the process for reinstalling Wordpress. The key here is that you have Debugging enabled on a production site which is not good. You should always have WP_DEBUG and WP_DEBUG_DISPLAY set to false in a production environment.