After updating to 1.9.2 I I had no more access to the admin page, therefore I logged to the connect manger page trying to reinstalling /Lib_ZF_Locale and others..
BUT unfortunately I had a big surprise "Magento's Installation Wizard"
http://mywebsite/downloader/index.php?A=loggedin#connect_iframe_result
Trying to proceed it gave me the error as below:
CONNECT ERROR: Failed to open file /home/*/public_html/downloader/.cache/community/Interface_Frontend_Rwd_Default-1.9.2.1/app/design/frontend/rwd/default/template/configurableswatches/catalog/product/view/type/configurable/swatch-js.phtml
I would be really happy to have your answer
Can you specify how many and which error you are facing when you update the Magento? So that I can help you out with exact solution.
Seems to be an old version of an extracted package that is blocking an unpacking operation in the downloader/.cache/community directory, removing the existing extracted package and re-running the upgrade solves the problem, maybe there should be pre-cleanup run before the upgrade process.