Occasionally I get this error message during the trading day. If it continues to repeat, the only solution is to restart WL. See attachment below.

1) Is this something (an update?) happening on the server side, and it has nothing to do with the WL client? (WL simply reports it as information.)

2) Does the /atp/ cited in the error message stand for Active Trader Pro (which I don't use)? If so, how is the WL client configuration dependent on the ATP config?

While I have no idea regarding this error message let me chime in for a couple of unrelated hints:

Hint 1: You should really stick with PNG as JPG is truly suboptimal for screenshots. If you haven't seen this famous comics, it's perfect time :)

JPEG or PNG – Which Image Format Offers Better Quality?

Hint 2: Modal windows allow their content to be copied simply by Ctrl-C.

On second thought, I can suggest something. If this error message pesters then you could employ AutoIT to have it closed automatically. Or even something as simple as a VBScript:

VBScript to detect an open messagebox and close it

And to figure out what's causing the obscure error and give the developers at Fidelity a clue you might want to enable logging:

Accessing Wealth-Lab Error Log

QUOTE:
Hint 1: You should really stick with PNG as JPG is truly suboptimal for screenshots.

I totally agree when there's text in the image--especially small text--but GIF only supports 256 colors, which looked really bad with this particular screenshot. The problem is there are too many tint levels in this image for GIF to render well. I probably should have cropped it to minimize the number of shades/tints present, then used a 256 color GIF. :(

PNG should work the best, but it will be 2.5 bigger than JPG. I would typically use PNG over JPG when small text is in the image. But in this case, the small text came through "somewhat okay" with JPG, which is 2.5 times smaller than PNG.

I think this is a WL "information message" rather than an error message, so I'm not sure if it would show up in a debug trace. But I didn't realize the WL client was configured from an ATP config on an external server. I wish Fidelity wouldn't change that config in the middle of the trading day.

I leave my error logging level set to "Error," which doesn't seem to generate too much disk overhead. WLP seems to be installed with this error logging level enabled.

QUOTE:
how is the WL client configuration dependent on the ATP config

Absolutely ZERO.

The url (in the WLP config file) points to the OLTX trade server. ATP and WLP trades go to the same place. Why that error occurs? We cannot tell, but it's the first time I can remember seeing it. Occurs frequently for you, does it?

QUOTE:
The url (in the WLP config file) points to the OLTX trade server ... [filling both] ATP and WLP trades ... Occurs frequently for you, does it?

It doesn't occur that frequently. When it does occur, there's an error dialog generated for each instance of a streaming trading strategy.

I didn't think this was related to the WL client; I thought it was a server side thing everyone was seeing. Apparently, I'm wrong.

It "probably" occurs because of some network race condition between my network and Fidelity's. In other words, we are never going to reproduce the quick-network turn-around time that reveals this race condition. Let's just forget about it unless others (on faster networks) have similar problems.

But the solution to preventing network-resource race conditions between client and server is a properly placed scheduling semaphore in the comm code that guards against the race condition. It's the same solution that will fix the "Stuck Submitted" problem; that's a communication race condition between client and server as well, which leads to live lock in the pending trade order.

Again, let's not worry about it until others on faster networks (low ping time) also see this problem. I'm good.

I just wanted to mention that I got the same error again last Friday, 12/8/2017, but this time it was 30-minutes before the US market open and my single open strategy was not streaming. This problem may not even be related to any strategy.

The WL client does appear to recover successfully with a meaningful error message, so the client may be working as designed. If someone gets this error message without any strategies open, please report that.

Getting this error message almost every other day now. Attaching screenshot and log from WLP.txt file.
Is this a known issue?

See this very topic for workaround...

WLP 6.9.19: Error getting Configuration: Collection was modified after the enumerator was instantiated , post #3

...and this one for the reason:

WLP 6.9.19: Error getting Configuration: Value cannot be null , post #4