Problem: After upgrading from JNBridgePro 7.2 (or earlier) to JNBridgePro 7.3, your program using JNBridgePro, which previously worked without problem, now throws an IndexOutOfRangeException.

This is the sign of an incomplete upgrade. Your program, which now uses JNBridgePro 7.3 .NET-side components and 7.3-generated proxies, is still using the jnbcore.jar from an earlier version of JNBridgePro, and that is causing the problem.  To fix the problem, make sure your application is using the jnbcore.jar from JNBridgePro 7.3.  This might be as simple as adjusting your app.config file.