Any insights?

We're looking at the DEF ENV directive to set some things up as we start our application. Doing some very preliminary tests, it seems as though the BEGIN directive clears out anything that had been set. I thought this was setting the Windows Environment variables for the session, which I would think would be session-permanent.
Is BEGIN supposed to clear these out?

It looks like you're using HTTP 1.0. FedEx may be expecting 1.1.

Any insights? So we don't wander in the dark...

When stepping through, have you tried disabling the seterr in the process?
Do you have any system parameters set that might have some effect on this ('WL', 'WD', 'VW', etc.)?

If you ESCAPE before the WRITE, you can step through it. The embedded IO routing will be steppable and you can find the offending situation that way.

Documentation indicates *obj/json was implemented last year: PxPlus 2025.

We're finally moving off 2018 (v15.10) ourselves soon, and will be glad to have the various new objects and tools available.

How about creating a PDF and downloading it?

Global variables are only active within a session, not between sessions.

Have you tried starting with numeric values to convert to Boolean? Would this work?

DEF OBJECT v,"*VARIANT"
v'val=1
v'type$="B"
PRINT v'val
-1
v'val=0
v'type$="B"
PRINT v'val
0

Have you tried passing "true" or "false" instead of 1 or 0?

Registration ran fine.

Has the program started? It's been about 1/2 hour since scheduled start, and still in the waiting room.

The client (WindX) is the client. The server (Linux, Unix, Windows, etc.) is the server. One side of the client-server pair can talk with the other side, regardless of the mix.

Caveat: If you have system calls to one type of server (e.g., Linux), they may need to be modified or changed to retrieve the desired information from another server (e.g., Windows).

This probably doesn't have a bearing on the situation, but do you have <CR> characters with the <LF> where POSTMAN does not?

The downloads only seem to have updates for Windows and WindX. Do the updates affect any of the other builds?