Segmentation fault (core dumped) | Stockfish | Page 1

lunar mountain Jul 13, 2025, 8:09 AM

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hi i tried in the cli to find the best move for this valid fen notation "1r2k2r/5pb1/2p1p1p1/1pnpPn1p/3R1P1P/1P3P2/PqP1Q3/2KR4 b k - 5 27" but after go depth i get an. Segmentation fault.

position fen 1r2k2r/5pb1/2p1p1p1/1pnpPn1p/3R1P1P/1P3P2/PqP1Q3/2KR4 b k - 5 27
go depth 7
info string NNUE evaluation using nn-ad9b42354671.nnue enabled
Segmentation fault (core dumped)

does somebody know how to fix this? thanks 🙂

shy sinew Jul 13, 2025, 8:21 AM

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Looks like the fen isn't valid, my own engine also crashes on an aseert

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lemme check

onyx turret Jul 13, 2025, 8:21 AM

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Black to move while white in check

tawny latchBOT Jul 13, 2025, 8:22 AM

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1r2k2r/5pb1/2p1p1p1/1pnpPn1p/3R1P1P/1P3P2/PqP1Q3/2KR4 b k - 5 27Lichess Link | Image

lunar mountain Jul 13, 2025, 8:33 AM

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eval just works fine. but go depth crashes

dusk bobcat Jul 13, 2025, 8:34 AM

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obviously.. illegal fen

lunar mountain Jul 13, 2025, 8:38 AM

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why is it an illegal fen?

shy sinew Jul 13, 2025, 8:38 AM

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because black is to move while white is in check

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so black can capture the king

lunar mountain Jul 13, 2025, 11:42 AM

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oh ok thanks, do u have any clue how to detect those cases, when i try to programm (python) a chess game engine (for like AI vs stockfish)?

onyx turret Jul 13, 2025, 11:43 AM

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Use the chess library

dusk bobcat Jul 13, 2025, 11:47 AM

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i.e. https://python-chess.readthedocs.io/en/latest/

lunar mountain Jul 13, 2025, 11:49 AM

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i am using this but i dont find any methode to detect it 😦

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i am using simplEngine for stockfish. i am letting alternating my ai and stockfish do a move. when stockfish is in a postion like this it should end the game. is there a way?

dusk bobcat Jul 13, 2025, 11:55 AM

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https://python-chess.readthedocs.io/en/latest/core.html#chess.Board

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is_valid()

shrewd wren Jul 28, 2025, 1:41 PM

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I guess OP should check is_game_over() before sending new position to the next engine

gray salmon Aug 4, 2025, 2:54 PM

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Please note that passing weird chess positions in chess, let alone illegal position, to Stockfish, is an undefined behavior.

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Stockfish optimizes for typical chess games that humans or machines could face.

#Segmentation fault (core dumped)