Hello Vagelis Kretsimos,
Is your path to the old project like this: /test/Sitefinity/Default.aspx
or just /test/Default.aspx
. Please try to remove "Sitefinity" from the url and see what the result will be.
The reason why there is "Sitefinity" in the url is due to the fact that we made some changes in the folder arrangement. In older versions, all the administration stuff was located in YourProject\Admin
folder but as this is a very common folder name which might be used by our clients we decided to move the Admin content to a new folder - Sitefinity, creating one more hierarchy step. And as the urls in the project manager are created with concatenation, the word "Sitefinity" appears.
Let us know if this is not the case.