A method, apparatus and computer program are disclosed for modifying an application comprising a plurality of modules. A user is presented with a list of modules. The user is able to specify input regarding any permitted version modifications for the modules listed. It is then determined whether the requested modifications are possible with one or more failure messages being output when any of the requested modifications are not possible. At least one of the failure messages is used to enable modification of the initial input provided by the user. In one embodiment, information is provided to the user based on one or more failure messages in order to enable the user to modify their choices. In another embodiment, the initial input is automatically modified. A permitted version modification may be, for example, a version upgrade, a version downgrade, and an indication that there is no preference.