Blank Administrator Page - Joomla! Forum - community, help and support

i saw post referring in april outdated , not think applies.
i ran update week ago through administrator panel (update tab) , seemed fine when done. not until logged out realized end no longer accessible. page blank , no source code.
has run or knows how troubleshoot it. front end fine unless try log in. solved without full rollback.
thanks in advance.

first, backup files, messed up. site backup welcome, before huge interventions.

edit configuration.php file

code: select all

change this:
public $debug = '0';

to this:
public $debug = '1';

and

code: select all

change this:
public $error_reporting = 'default';

to this:
public $error_reporting = 'maximum';

maybe way can error messages, help. if so, come , post them.