user10983: We know that despite what is shown in the movies and such, most chess games don't end by a "checkmate" move and oftentimes one side realizes that they are losing and resigns before the end. Now this begs the question: Has there been any serious games in the history of chess that the resignation was itself a blunder? Meaning that, the person who resigned had a chance of winning that they missed to spot at the time.
By serious game I mean a GM-level (or if there is none, a near-GM-level) match. To be more specific, let's exclude the timed games that the possibly-winning side has lost by timeout. Also there was some games that one side deliberately resigned due to some personal reasons. Those are also not the ones that I am looking for.

user4399: Sure. See Wiki: Resignation in won positions. Some examples:

Ignatz von Popiel vs. Georg Marco 1902

Gyorgy Negyesy vs. Karoly Honfi 1955

Raul Sanguineti vs. Miguel Najdorf

Victor Korchnoi vs. Geert van der Stricht


Even Karsten Müller in h endgame series talks about how GMs (or at least pros) have resigned in drawish(/winning?) positions.

user12: The official source that people link to when this question comes up is Tim Krabbe's excellent blog post from more than 20 years ago now: The ultimate blunder. He collected every single game in the database (pre 1999) where someone resigned in a winning position and explained the possible reasons behind the resignation for each game as well.
Some very famous examples include:
[White "Von Popiel"]
[Black "Marco"]
[Title "Von Popiel-Marco, Monte Carlo 1902"]
[FEN "7k/1b1r2p1/p6p/1p2qN2/3bP3/3Q4/P5PP/1B1R3K b - - 0 1"]

"This is the earliest, the most famous, and still the clearest example of this blunder. Black resigned because he saw he was going to lose the Bd4. He could have won on the spot with 36...Bg1"
[White "Torre"]
[Black "Parker"]
[Title "Torre-Parker, New York 1924"]
[FEN "2kr4/ppp3Pp/4RP1B/2r5/5P2/1P6/P2p3P/3K4 w - - 0 1"]

"The Mexican grandmaster did not see what he could do against Rc1+ and promotion, and resigned. With 1.Rd6! he could have saved the day, and even have won: e.g. 1...Rxd6 2.g8Q+ Kd7 (Rd8 3.Qxd8+ and 4.f7) 3.Qf7+ Kc6 4.Qe8+ Kb6 5.Qe3 Kc6 6.Qxc5+"

10983: <p>We know that despite what is shown in the movies and such, most chess games don't end by a &quot;checkmate&quot; move and oftentimes one side realizes that they are losing and resigns before the end. Now this begs the question: Has there been any serious games in the history of chess that the resignation was itself a blunder? Meaning that, the person who resigned had a chance of winning that they missed to spot at the time.</p>
<p>By serious game I mean a GM-level (or if there is none, a near-GM-level) match. To be more specific, let's exclude the timed games that the possibly-winning side has lost by timeout. Also there was some games that one side deliberately resigned due to some personal reasons. Those are also not the ones that I am looking for.</p>
 4399: <p>Sure. See <a href="https://en.wikipedia.org/wiki/Blunder_(chess)#Resignation_in_won_positions" rel="nofollow noreferrer">Wiki: Resignation in won positions</a>. Some examples:</p>
<ol>
<li><p>Ignatz von Popiel vs. Georg Marco 1902</p>
</li>
<li><p>Gyorgy Negyesy vs. Karoly Honfi 1955</p>
</li>
<li><p>Raul Sanguineti vs. Miguel Najdorf</p>
</li>
<li><p>Victor Korchnoi vs. Geert van der Stricht</p>
</li>
</ol>
<p>Even Karsten Müller in <a href="https://chess.stackexchange.com/questions/35641/practical-endgame-resources-whats-next-after-josh-waitzkins-series-in-chess/36829#36829">h endgame series</a> talks about how GMs (or at least pros) have resigned in drawish(/winning?) positions.</p>
 12: <p>The official source that people link to when this question comes up is Tim Krabbe's excellent blog post from more than 20 years ago now: <a href="https://timkr.home.xs4all.nl/chess2/resigntxt.htm" rel="noreferrer">The ultimate blunder</a>. He collected every single game in the database (pre 1999) where someone resigned in a winning position and explained the possible reasons behind the resignation for each game as well.</p>
<p>Some very famous examples include:</p>
<pre><code>[White &quot;Von Popiel&quot;]
[Black &quot;Marco&quot;]
[Title &quot;Von Popiel-Marco, Monte Carlo 1902&quot;]
[FEN &quot;7k/1b1r2p1/p6p/1p2qN2/3bP3/3Q4/P5PP/1B1R3K b - - 0 1&quot;]
</code></pre>
<p>&quot;This is the earliest, the most famous, and still the clearest example of this blunder. Black resigned because he saw he was going to lose the Bd4. He could have won on the spot with 36...Bg1&quot;</p>
<pre><code>[White &quot;Torre&quot;]
[Black &quot;Parker&quot;]
[Title &quot;Torre-Parker, New York 1924&quot;]
[FEN &quot;2kr4/ppp3Pp/4RP1B/2r5/5P2/1P6/P2p3P/3K4 w - - 0 1&quot;]
</code></pre>
<p>&quot;The Mexican grandmaster did not see what he could do against Rc1+ and promotion, and resigned. With 1.Rd6! he could have saved the day, and even have won: e.g. 1...Rxd6 2.g8Q+ Kd7 (Rd8 3.Qxd8+ and 4.f7) 3.Qf7+ Kc6 4.Qe8+ Kb6 5.Qe3 Kc6 6.Qxc5+&quot;</p>
