Current issue with PEAR repositories affects upgrade from Magento 220.127.116.11 to Magento 18.104.22.168 via Magento Connect Manager and installation of some Magento extensions. The following error (or similar one) is shown in Magento Connect Manager on installation/upgrade:
ERROR: unable to unpack downloader/pearlib/download/AW_Blog-1.0.21.tgz
To solve the issue it is needed to forcibedly upgrade PEAR package to the latest version using the following CLI command:
./pear install -f PEAR
For new Magenting installations this command is included in the post-install script. If you notice this issue with your old Magento installation, please notify the Support Team to get this fixed.