Hello everyone.
I upload manually the wordpress version from 3.5 to 3.8.1 (I didn´t want to make the auto upgrade to the 4.0 becouse I am using not compatible plugins with newer than the 3.8.1).
To make this I follow this steps: http://codex.wordpress.org/Upgrading_WordPress#Manual_Update
But after make everything I found many problems, on a begining I couldn´t access to the admin site, I maked a database upgrade (using the wp-admin/upgrade.php) and I refreshed all the folders (except wp-content and the single files like config.php...).
After that I could pass into the wp-admin. But now, on the admin site I see this:
Warning: call_user_func_array() expects parameter 1 to be a valid callback, function '_show_post_preview' not found or invalid function name in /thehost/wp-includes/plugin.php on line 429
I see that it was by plugins, so I try to uninstall all... after all uninstall the wordpress fire a problem and the "back-office" doesn´t works, but when I return back (modifying the url) to the plugins place, the plugin had been removed, except one.. there is one that there is no way to uninstall (contact-7-form).
Also, if I try to open the web without an admin acount openned on the browser, the web doesn´t works... it fires this:
Warning: call_user_func_array() expects parameter 1 to be a valid callback, function '_show_post_preview' not found or invalid function name in /homepages/4/d385538560/htdocs/almendros/wp-includes/plugin.php on line 429
Warning: Cannot modify header information - headers already sent by (output started at /thehost/wp-includes/functions.php:2908) in /theshost/wp-includes/pluggable.php on line 896
Any idea??
Thank you very much.