From 4cb32467d34e6331b42bf45659ebb6de9e8198d2 Mon Sep 17 00:00:00 2001
From: Starkiller1St <39921115+Starkiller1St@users.noreply.github.com>
Date: Sat, 20 Dec 2025 15:13:04 +0100
Subject: [PATCH] Fix singleplayer lockout when changing password (#16673)

---
 src/network/serverpackethandler.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/network/serverpackethandler.cpp b/src/network/serverpackethandler.cpp
index 62ed782da..20c37ec22 100644
--- a/src/network/serverpackethandler.cpp
+++ b/src/network/serverpackethandler.cpp
@@ -1660,7 +1660,9 @@ void Server::handleCommand_SrpBytesM(NetworkPacket* pkt)
 	srp_verifier_verify_session((SRPVerifier *) client->auth_data,
 		(unsigned char *)bytes_M.c_str(), &bytes_HAMK);
 
-	if (!bytes_HAMK) {
+	// skip authentication check for singleplayer world.
+	const bool is_true_singleplayer = isSingleplayer() && (strcasecmp(playername.c_str(), "singleplayer") == 0);
+	if (!bytes_HAMK && !is_true_singleplayer) {
 		if (wantSudo) {
 			actionstream << "Server: User " << playername << " at " << addr_s
 				<< " tried to change their password, but supplied wrong"