1-0 Arena Adjudication. Illegal move!

On Arena 2.1 I go to try to vs. houdini 1.5 and here is the pgn

[White "Egg_nogin"]

[Black "Houdini 1.5"]

[Result "1-0"]

1.e4 e5 2.Nf3 ,... 1-0 Arena Adjudication. Illegal move!

this isn't just for Nf3 too other positions it says illegal move...

Is Houdini resigning because he is intimidated by my 1100 blitz rating and is making an excuse, or is this just a bug?

If you know how to make houdini more self confident or fix the bug I would like to know how. thanks 

I also am using arena (just got it) and have seen this error a few times. 

It is a bug of some sort in the software.  I do not yet know how to fix it other than exit the game and start a new game.   Its not the houdini engine, its something in arena that thinks moves are illegal all of a sudden, even legal moves.  Once it is broken, it stays broken.   I think the internal move list is corrupted and the board does not match what is in memory, so when you move what you SEE it really is an illegal move.  But that is just my best guess. 

Anyway, restart the program and try again.

The problem could be any number of things. You could try activating the debug window to see what kind of error is involved. (In the menu, "Engines -> Debug-Window".)

Just a question or two: Has the engine worked before? Did you install the engine as a UCI engine? Do other engines work?

Update - I started up my Arena 2.0.1 with Houdini 1.5, and it is giving me the same error message at times. I'll install Houdini 1.5a and see if that solves the problem.

You could try updating to the latest version of Arena: version 3.

Houdini 1.5a seems to be working for me in Arena 2.0.1. Regardless of which version of Arena you use, I'd go with Houdini 1.5a.

http://www.cruxis.com/chess/houdini.htm

@ EscherehcsE

I can't find the Houdini 1.5a download can you screen shot it please? 

The link is tiny, easy to overlook. It's juuuust above the Support section.

Same problem with Arena 3.0 and Houdini 1.5a. Arena sucks in so many ways. Why they hide so many ordinary functions behind user unfriendly interface is a mystery to me.

All I can say is that I've used Houdini 1.5a in Arena 3.0 a LOT, and it's been perfectly reliable for me.

reliable? yes. user friendly? no. and it's also a big minus that such a big bug already known in the version 2.1 made it to version 3.0

Which bug is that?

Arena isn't perfect, but it's a pretty good GUI. I do wish they'd fix the auto-analysis bug that doesn't analyze the last two moves of a game, and I also wish they'd fix the chess960 castling notation incompatibility. Other than those two items, I really have no complaints.

Sorry, I can't help.

its a bug. Checking the logs, the engine seems to think it's it's turn to move while it's actually opponent's turn, hence Arena declares an illegal move. A developer needs to look into this and correct the code. Seems Arena is receiving a 'phantom move' from somewhere and results in a conflict where both engines are pondering on the same move. The gui seems to think it's received a move from opponent when actually it hasn't. Where are we supposed to report these kind of issues?? some bit of the log below:
2020-08-16 11:47:32.135<--1:bestmove b7b5 ponder d1a1 2020-08-16 11:47:32.135*moveerror* black moved but it is white's turn !b7-b5! 2020-08-16 11:47:32.135*moveerror* R illegal move detected by movegen, sorry, no more details !...! 2020-08-16 11:47:32.135*1*---------> Arena:Illegal move!: "bestmove b7b5 ponder d1a1" () 2020-08-16 10:00:42.481<--1:info depth 11