For example, if you launch UE4.10 and choose to open a project from a previous version, be sure to select the option of “Open a Copy” instead of overwriting the original previous version with UE4.10.
For example, if you launch UE4.10 and choose to open a project from a previous version, be sure to select the option of “Open a Copy” instead of overwriting the original previous version with UE4.10.