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Bug report: Local analysis spitting out nonesense illegal move.

After analyzing my last game locally via LiChess on my laptop, the analysis showed a weird moment where the eval dropped a lot. When inspecting this moment, the line the engine showed was full of illegal moves, including captures of own pieces, rooks moving diagonally and knights moving like pawns. See attached images for the setting used to run the local analysis and the moves that the engine suggests.
Schermafbeelding 2026-10-17 163810.png
Schermafbeelding 2026-10-17 164049.png
Schermafbeelding 2026-10-17 163849.png
Schermafbeelding 2026-10-17 164057.png
Schermafbeelding 2026-10-17 164104.png
Schermafbeelding 2026-10-17 164039.png
Schermafbeelding 2026-10-17 163856.png

After analyzing my last game locally via LiChess on my laptop, the analysis showed a weird moment where the eval dropped a lot. When inspecting this moment, the line the engine showed was full of illegal moves, including captures of own pieces, rooks moving diagonally and knights moving like pawns. See attached images for the setting used to run the local analysis and the moves that the engine suggests. ![Schermafbeelding 2026-10-17 163810.png](https://image.lichess1.org/display?op=noop&path=z6HU-4s201QW.png&sig=305b394e0af0dd0d010452a63e6c7bc0fae8e3ca) ![Schermafbeelding 2026-10-17 164049.png](https://image.lichess1.org/display?fmt=png&h=0&op=resize&path=-by0Le_lfXh2.png&w=864&sig=82440f8711e2a9438e44ff41b03bba9ed24eefb8) ![Schermafbeelding 2026-10-17 163849.png](https://image.lichess1.org/display?fmt=png&h=0&op=resize&path=Vx4XG8-InCu6.png&w=864&sig=3f20ec1abc89355e9db62bdf4b397e91e268b5ed) ![Schermafbeelding 2026-10-17 164057.png](https://image.lichess1.org/display?fmt=png&h=0&op=resize&path=n1LvcNUoELG_.png&w=864&sig=017623c963d46e4b845de8e77813960278f19cc5) ![Schermafbeelding 2026-10-17 164104.png](https://image.lichess1.org/display?fmt=png&h=0&op=resize&path=O3YTxywaSOC-.png&w=864&sig=d0f1d2971df7d2e28a50bf2e77cac1d240decc77) ![Schermafbeelding 2026-10-17 164039.png](https://image.lichess1.org/display?fmt=png&h=0&op=resize&path=1NHB0jGkiIGh.png&w=864&sig=e437a8e67e5d6dd959ee4c01f6ce5c4c53058f08) ![Schermafbeelding 2026-10-17 163856.png](https://image.lichess1.org/display?fmt=png&h=0&op=resize&path=dbKti8KyMITS.png&w=864&sig=355bdf7ed83f6b026665f41b69098db1a369e8ad)

Nd1=Q eh? Bold.

Can you tell me your browser so I know which javascript engine ran this, and also - has a browser Stockfish ever given you obviously wrong evals like this before?

Nd1=Q eh? Bold. Can you tell me your browser so I know which javascript engine ran this, and also - has a browser Stockfish ever given you obviously wrong evals like this before?

Hi, thanks for your response. I am using Firefox Version 158.0.1 (64-bit). A browser Stockfish has not given me anything similar before, also not on the same game. Hopefully you can fix it, as the local analysis is a cool feature!

Hi, thanks for your response. I am using Firefox Version 158.0.1 (64-bit). A browser Stockfish has not given me anything similar before, also not on the same game. Hopefully you can fix it, as the local analysis is a cool feature!

I think that ChatGPT took over stockfish's job of analyzing the game for a second, actually though this is really weird.

I think that ChatGPT took over stockfish's job of analyzing the game for a second, actually though this is really weird.