Is it possible to upgrade a project built in UE3 to UE4?

I have a project built in UE3 in hand, but I want to further develop it in UE4.
So, is it possible to convert that project to UE4?
I found some answers after searching Google, where all are about upgrade from previous versions in UE4(like 4.2, 4.3) to newer versions in UE4(like 4.9, 4.10).

Short answer: No.
Long Answer: No, there are many incompatibilities between UE3 and UE4, so an automatic upgrade is not possible. However, you can still use your original assets with UE4 and recreate the project from scratch.

How large is your project? That’s probably the dictating factor in how long it will take to rebuild it in UE4.

I did it with one project, and it was fairly quick, but there were only 2 animated characters.

There isn’t a one-stop shop or tool created by Epic etc, but here are some options:

As to whether its worth it… If the game is simple or you’re superhuman like Hourences then yes.
But if you’re a mere mortal like most then it might be worth finishing the project in UE3 instead.
Especially so if physics or vehicles are a big part of the game and both are already working well.
Also be aware that Epic UE3/UDK assets can’t be used in UE4 because of ongoing legal limbo…