diff -rupN --no-dereference qtbase-everywhere-src-5.15.12/src/network/kernel/qauthenticator.cpp qtbase-everywhere-src-5.15.12-new/src/network/kernel/qauthenticator.cpp
--- qtbase-everywhere-src-5.15.12/src/network/kernel/qauthenticator.cpp	2023-10-17 14:50:53.000000000 +0200
+++ qtbase-everywhere-src-5.15.12-new/src/network/kernel/qauthenticator.cpp	2024-02-15 09:58:52.002172690 +0100
@@ -603,11 +603,13 @@ QByteArray QAuthenticatorPrivate::calcul
         break;
     case QAuthenticatorPrivate::Negotiate:
         methodString = "Negotiate";
-        if (challenge.isEmpty()) {
-            QByteArray phase1Token;
 #if QT_CONFIG(sspi) // SSPI
+        if (challenge.isEmpty() || !sspiWindowsHandles) {
+            QByteArray phase1Token;
             phase1Token = qSspiStartup(this, method, host);
 #elif QT_CONFIG(gssapi) // GSSAPI
+        if (challenge.isEmpty() || !gssApiHandles) {
+            QByteArray phase1Token;
             phase1Token = qGssapiStartup(this, host);
 #endif