Launch the project:upgrade1.1 task from your project directory to perform an automatic upgrade. It's useful to save a copy of the log.
$ ./symfony project:upgrade1.1 > log/upgrade1.1.log
If you have the tee command available (standard on UNIX/Linux, available in Cygwin for Windows), then
$ ./symfony project:upgrade1.1 | tee log/upgrade1.1.log
$ ./symfony project:upgrade1.1 2>&1 | tee log/upgrade1.1.log
can be more convenient.
This task can be launched several times without any ill effects. Each time you upgrade to a new symfony 1.1 beta / RC or the final symfony 1.1, you must run this task.
Next step: If necessary, turn on Compatibility Mode.