Reasons for subsequent Broken/missing handler in Views?
Please follow the following guides:


Upgrading Drupal core
Migrating D6 Content Construction Kit (CCK) to D7 Fields
Migrating image fields


Also:


Make sure that you've enabled all the field modules such as image and views related 
Changed field type: The 'field_source_file' field type
will be changed from 'filefield' to 'file' is just information; it's nothing to worry about
To fix the Broken/missing handler message, you have to identify the right modules which provide these handlers and enable them