Could not determine temp directory, please specify a cache_dir manually

I just wanna share you guys my experience problem how to resolve the " Could not determine temp directory, please specify a cache_dir manually " error message in Magento. This error sometimes ossurs when you are trying to access some areas of the Magento admin panel.

1) Open Magento root directory and create tmp folder.

2) Set directory permissions to 777 or 755

2) Open "lib/Zend/Cache/Backend/File.php", and locate the following code

PHP Code:

---

protected $_options = array(
'cache_dir' => null, 


---

replace with

PHP Code:

---

protected $_options = array(
'cache_dir' => 'tmp', 


---

I meet the same problem and it work very well with your solution. Thanks
I am wondering if anyway else we can fix without core edit?