New Magento 1.4 brings changes in how errors are displayed along with an easy way to put your favorite store into maintenance mode.
If you check index.php file of new Magento 1.4, you’ll notice one interesting thingy, it checks for existence of “maintenance.flag” file in store root, if it’s found your store is put into maintenance mode. Service Temporarily Unavailable page is displayed with Please try again later message. Remember that administration can’t be accessed in maintenance mode along with the store.
Developers probably noticed that errors also are no longer displayed like before, as mentioned on Magento blog:
Since version 184.108.40.206 for security reasons the trace in the Magento error report page is disabled by default. The “Error log number” does not give any information about the error. To enable the trace copy the errors/local.xml.sample to errors/local.xml and follow the instructions described in that file.
By default, error logs are placed in /var/report, named by mentioned log number. local.xml file is well commented, so open it and check possible configuration options. I really like emailing of error reports to specified email address.
If you want to change default maintenance look, you can change
Till next time 😉