i keep getting
[LTN] No train to transport from [Train stop: Natalia Wydra] to [Train stop: Kotasienka] in networks Ox4 with length between 1 and 100 found in depot.

I have a train in the network with 2 locomotive and 1 cargo wagon at the depot
here is a blueprint of the setup i am trying to use
"
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"

Yes. This is fixed in 2.7.0.

I am suddenly getting this error now, on LTN 2.8.1 Factorio 2.0.77. Only for a few certain stations though...

do you have a save that I can look at?

I'm getting this error now on LTN 2.8.1, factorio 2.0.77. It is similarly only for a few stations. Notably, I am playing with Pyanodons, and I am getting the error only with one of the "hydrogen" pickup stations. (I also had the error with a "Tin (grade 1) station, but I think that one was an error on my part. I've uploaded a save to the following link: https://drive.google.com/file/d/1Ct0Dy23jQL7g53FhgwhFJIebT5OJfXqU/view?usp=drive_link

Hope it helps!

Thanks. Will take a look.

"You need access" - https://drive.google.com/file/d/1Ct0Dy23jQL7g53FhgwhFJIebT5OJfXqU/view?usp=drive_link

I guess you need to make this public.

Thanks for sharing the map. I now have a rough idea what happens (and some more ideas on how to fix it).

Currently, when addressing a delivery, all potential providers are enumerated, sorted and then the "best fit provider" is chosen. This comes from the assumption that 'every train in every depot can go to every provider'. Now LTN selects a train from the pool of available trains and it does so by also checking the path length from the depot to the provider. In the past, this was a simple "straight line between the depot and provider", shortest distance calculation and then the delivery got scheduled. Now, LTN actually asks the game with LuaTrainManager#request_train_path and what happens is that there is no train that has a route to the chosen provider. In case of the "hydrogen", there are actually multiple stations providing it but the one that was chosen, there is no path (there are paths to all the other ones).

This complicates things. Basically, LTN needs to determine for all potential providers whether there is a train that can travel to it. So instead of "one requester -> one provider -> find pool of trains, select one", this is now "one requester, multiple providers, find for each provider a pool of trains that can travel, then choose a provider / train combination that is "best fit".

I have started poking at that but it will take a bit longer to actually work (and then I need to make sure that I don't break all the other things like reverse trains, Space Exploration travel through elevevator etc).

You can actually validate this by clicking on the "Hydrogen Pickup" that is shown in the message, then renaming this stop to something else (so that it is unique) and then trying to send a train there. The stop shows up as red for me which means, trains can't actually go there.

The other issue that I see with the map (which may be intentional) that some of your stations don't have a network id set and the default network id is 0. I'm not sure whether this is how you turn stations on/off or just an oversight.

However the problem of "electing a stop that is inaccessible" is a problem with LTN.

There is a chain signal on the wrong side of the tracks for the inaccessible hydrogen pickup.