The full error looks like this:
You might see this nagging error every once you install something to your Joomla site. Apparently everything working, but - as any errors you see - should alert you: something isn't right with your site, and even if apparently everything works, you might have unexpected problems later!
The error can have multiple sources, but the most common cases are having a common source: the site was recently moved (from development environment to live site or from one server to another) and settings related with two key folders, the log and the temporary folders weren't changed/tweaked to match the actual server configuration.
How you can avoid this and if you're in trouble, how you can fix it?
Best way to avoid it to use Akeeba Backup for relocating your site, and when you restore te site on it's new place, be sure to check the checkbox near "Use the new server paths for your log and temp directories" to avoid these problems.
But if the damage is already done, you need to fix it. It's simple, you need to edit the configuration of Joomla.
The best case is if you can do the edit and to save the result from the Joomla's Global Configuration panel. But if, for some reason this don;t work, you need to manually edit the configuration.php file.
Be aware, that this qualifies as core hack, so act accordingly - do a backup first, and be sure, that you can restore the original file if something goes wrong!
Open your configuration .php file, and locate the string:
This will contain the Directory path of your Old Server. Just replace the whole line with the code below - or with the physical path of your logs directory (see this tip!):
var $log_path = './logs';
Then locate this code:
which also contains the Directory path of your Old Server. Replace the whole line with the code
var $tmp_path = './tmp';