If debug parameters have been added to Domino for other issues they may cause the installer for LEI to fail with java.lang.NumberFormatException or other Java errors.
You encounter java errors when hitting Next, after supplying names for the LEI and Domino servers. They may be similar to this:
This is the first time that the the java based installer begins to communicate with the Domino server through an API.
This issue has been seen on Windows and System i, and likely affects all platforms.
Resolving the problem
Temporarily remove DEBUG_INITTERM and other debug parameters, then restart Domino, before running the LEI installer. You may add them back after the LEI installation completes.