I think Lucas-san try to save like “save as”, in older version and can work, but from ue4 for ue3 ?
I suppose if are from ue4 4.76 to 4.8.1, for example it
should be possible, given the difficulties that sometimes found in moving into new versions with the inherent problems in addition.
For I dont not know if it’s possible but it was convenient, a backup version to have, you can count on.
If anyone knows answer this question, surely will help a lot of undecided people in moving on to more current versions.