admin-header.php workings

Hi all,

While trying to auto update my 3.1.4 install the update crashed and delivered an “admin-header.php fault on line …..” error message on the domain and admin access.

In trying to gain access I uploaded an old admin-header.php file. All worked again but any plugin update or install gives a “Could not create directory. /wordpress” error.

I did try to find a solution on the forum with various searches, but could not find related discussions. In trying to leverage the differences in the admin-header.php files, I found my knowledge is insufficient to tackle the issue.

What best to do? What is the admin-header.php function in all this, if any?

Help or pointers appreciated.