Have you tried:
– deactivating all plugins to see if this resolves the problem? If this works, re-activate the plugins one by one until you find the problematic plugin(s).
– switching to the default theme to rule out any theme-related problems?
– resetting the plugins folder by FTP or phpMyAdmin? Sometimes, an apparently inactive plugin can still cause problems.
Just had almost the same problem (only “Argument #1”) when I just upgraded to 2.9.1, but only sometimes. It seems to be caused if there are GET or POST parameters (Argument #1 and #2, respectively) in the request but these are unset by a plugin, which in my case is a modification I made to better combine Language Switcher and WP Super Cache.
I added the line
if (!isset($_GET)) $_GET=array();
before the array_merge line 637, and my warnings are gone. For the “Argument #2” warning, a similar line would be needed for $_POST; however, this probably won’t help you with your new post problem – since the important post data is apparently missing from the request – and you’re gonna have to try esmi’s hints. It might help searching your plugin files for unset($_GET) and unset($_POST) (note that there might be additional blanks around the parentheses).
(Edit: On a second thought and more investigation, I rather changed my aforementioned modification, since that was my only cause, so no core file mod needed for me…)
@esmi I tried to change the theme but it says that I couldn’t do it (the same message when Im trying to post something) it tried to deactivate all plugins but it doesnt let me do it too =(
Right now I am trying to resetting the plugins (I will let you know, when im finished)
And thank you cimddwc for your advice I will try to do my best, and let you know guys!
I reset the plugins folder and it seems to work ! I already posted something and it works, I will upload plugin by plugin so I can check which one gave me the problem.
thanks guys!
I want to tell you that the plugin that was giving me the problem is wpClassified Version 1.3.1-b
