Yii2 version upgrade from 2.0.4 to 2.0.6 implementation process;
1. Open the URL,http://www.yiiframework.com/download/,根据提示执行升级:
2. Execute the command: php composer.phar require yiisoft/yii2 2.0.6, report an error:
[UnexpectedValueException]
Could not parse version Constraint <=2.*: Invalid version string “2.*”

Execute the upgrade command and report an error: Could not parse version Constraint <=2.*: Invalid version string “2.*”
3. Execute commands one after another: composer self-update, composer global update;
4. Execute the command again: composer global update;
5. Execute the command again: php composer.phar require yiisoft/yii2 2.0.6, the upgrade is successful;
6. Screenshot of logging in the SVN repository:




