Changed project file format: The file format of project files has changed from version 2.x. Together recognizes the version 2.x project file format and converts it to a new format after saving the old version as ~oldname.tpr. If you will still want to open the same project in version 2.x, you should open the .tpr file with the "~" prefix. Note the information in the next paragraph, however.
Changed diagram file format: The file format of diagram files has also changed from version 2.x. The file extension of Together diagrams has changed from.vfDiagramType to .dfDiagramType. Together recognizes your version 2.x diagrams and creates copies in the new format with the same file name and the .df* extension. These copies appear in the Model tab of the Explorer, and you can open and edit them usingTogether 3.0 or above. Your version 2.x diagrams are unaffected. If you keep your diagram files under version control, you will need to add the new .df* files to your version control project.
IMPORTANT:
When you modify diagrams (having .df extensions) that were converted from 2.x diagrams (having .vf extensions), the version 2.x diagrams are not updated. Anyone using version 2.x and opening the 2.x project file (~oldname.tpr) will not see such modifications. Therefore, you should restrict your critical development to version 2.x until you are ready to upgrade all users on a given project at the same time. If you are using version 2.x and are only evaluating Together (3.0 or above) to see if you want to upgrade, do not use the new version to modify anything that is critical to your development until your are ready to upgrade.