Reasons for subsequent Broken/missing handler in Views? In the process of upgrading Drupal 6.x to 7.x I'm facing a problem that makes all my views show nothing relevant. (I believe the problem is here but I'm not sure, I don't know. That's why I'm asking):

After using the migrate field from CCK module in Drupal 7.x most of my views end up with Broken/missing handler whether it is in Field, Filters Criteria or Relationships.

On the other side, when using the migrate field module, most of the fields have a message similar to this attached with them. (The field names change.)


  Missing formatter: The 'hidden' formatter used in 3 view modes for the field_phone field is not available, these displays will be reset to the default formatter.


Or I get this message. 


  Changed field type: The 'field_source_file' field type will be changed from 'filefield' to 'file'.


Or I get this message one too.


  The field uses the view list_of_project_for_captain_log to determine referenceable nodes. You will need to manually edit the view and add a display of type 'References'.


Is this the reason why most the views have a Broken/missing handler than makes them not work properly? If yes, what can I do, if not what else could be the reason for such problems and what should be done?
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