I have created a project in Premiere Elements v12, but when I try to load the xx.prel file in my new Premiere Elements v14 to modify it, I get an error message "This file type is not supported or the required codec is not installed". Which codec do I need to install and how can I do that? or is there another way to convert a xx.prel file form version 12 to 14?
You're trying to load the project using Add Media. To open a project, go to the File menu and select Open Project.
Although I kind of recommend against trying to open a project created with an older version of the program using a newer version of the program. Premiere Elements isn't designed to do that, and it can lead to bugginess or even total file corruption.
We always recommend finishing a version 12 project in version 12 and only work on version 14 projects in version 14.