Usually, when an external procedure fails, its C prototype is faulty.

That is, the prototype does not match the one generated internally by PL/SQL. This can happen if you specify an incompatible C data type. For example, to pass an OUT parameter of type REAL, you must specify float *. Specifying float, double *, or any other C data type results in a mismatch.

In such cases, you get a lost RPC connection to external procedure agent error, which means that agent extproc terminated abnormally because the external procedure caused a core dump.

• Using Package DEBUG_EXTPROC
  To help you debug external procedures, PL/SQL provides the utility package DEBUG_EXTPROC.