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when posting a comment I got the follow error,

Warning: call_user_func() [function.call-user-func]: First argument is expected to be a valid callback in /home/... .../wp-includes/functions.php on line 1904

Warning: Cannot modify header information - headers already sent by (output started at /home/... .../wp-includes/functions.php:1904) in /home/... .../wp-content/plugins/jetpack/modules/subscriptions.php on line 487

Warning: Cannot modify header information - headers already sent by (output started at /home/... .../wp-includes/functions.php:1904) in /home/... .../wp-content/plugins/jetpack/modules/subscriptions.php on line 492

Warning: Cannot modify header information - headers already sent by (output started at /home/... .../wp-includes/functions.php:1904) in /home/... .../wp-includes/comment.php on line 586

Warning: Cannot modify header information - headers already sent by (output started at /home/... .../wp-includes/functions.php:1904) in /home/... .../wp-includes/comment.php on line 587

Warning: Cannot modify header information - headers already sent by (output started at /home/... .../wp-includes/functions.php:1904) in /home/... .../wp-includes/comment.php on line 588

Warning: Cannot modify header information - headers already sent by (output started at /home/... .../wp-includes/functions.php:1904) in /home/... .../wp-includes/pluggable.php on line 881

can it be related to JETPACK plugin ???

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You need to paste in your question the full function which apears in line 1904 in your functions.php – Sagive SEO Jul 8 '12 at 1:31
Sagive that will not help, thats a Core function, complaining about a different function thats hooking in – Tom J Nowell Jul 8 '12 at 2:29
1  
If it is jetpack, disabling jetpack would remove these warnings. Disable jetpack and find out – Tom J Nowell Jul 8 '12 at 2:31

closed as too localized by toscho♦ Jul 8 '12 at 6:45

This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, see the FAQ.

2 Answers

up vote 1 down vote

best guess is that you're using a theme that's based off of twentyten or twentyeleven and aren't including the twentyten_comments() function from twentyten/functions.php into your functions file.

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Is this wordpress.org/extend/themes/zeemagazine the case? – qaedus Jul 8 '12 at 2:00
up vote 1 down vote

Those are not errors, those are warnings.

Configure your PHP to output to an error log rather than to the frontend, or at least to only display real hard errors. Logging to a file is always preferable to showing on the frontend ( with some minor exceptions )

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how do I do that? – qaedus Jul 8 '12 at 4:15
If you google you'll find hundreds of thousands of articles telling you how. It's a very common thing to do so I won't repeat it here – Tom J Nowell Jul 8 '12 at 13:03

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