When placing a blueprint the (presumably) requester station was placed before the rail was, and results in:

Error while running event UTLogistics::on_train_changed_state (ID 31)
Given train stop is not connected to any rails, cannot be used as a target
stack traceback:
    [C]: in function 'request_train_path'
    __UTLogistics__/scripts/dispatcher/reach.lua:73: in function 'check'
    __UTLogistics__/scripts/dispatcher/dispatch.lua:164: in function 'chain'
    __UTLogistics__/scripts/trains/init.lua:82: in function 'fn'
    __UTLogistics__/scripts/core/perf.lua:19: in function 'measure'
    __UTLogistics__/scripts/trains/init.lua:115: in function
    <__UTLogistics__/scripts/trains/init.lua:113>

I did a quick fix by adding a bailout-check to return false from Reach.check if not stop.valid or not stop.connected_rail

You'd probably want to check the stop has rail connected before even getting to this point though, so it's not even considered as part of the UTL network.

Thanks for the report and the trace! Fixed in 0.0.15: train stops without a connected rail are no longer used as a target (requesters, providers, depots, fuel and cleanup stations) until a rail is attached, so placing a blueprint where the stop comes before the rail no longer crashes. You can remove your quick fix after updating. The map setting "Debug log" now also writes a line when a train stop has no rail, in case something similar shows up again.