Index: ps/trunk/binaries/data/mods/public/gui/credits/texts/programming.json
===================================================================
--- ps/trunk/binaries/data/mods/public/gui/credits/texts/programming.json
+++ ps/trunk/binaries/data/mods/public/gui/credits/texts/programming.json
@@ -28,6 +28,7 @@
 				{ "nick": "Alan", "name": "Alan Kemp" },
 				{ "nick": "Alex", "name": "Alexander Yakobovich" },
 				{ "nick": "alpha123", "name": "Peter P. Cannici" },
+				{ "nick": "Ampaex", "name": "Antonio Vazquez" },
 				{ "name": "André Puel" },
 				{ "nick": "andy5995", "name": "Andy Alt" },
 				{ "nick": "Angen" },
Index: ps/trunk/binaries/data/mods/public/simulation/helpers/Commands.js
===================================================================
--- ps/trunk/binaries/data/mods/public/simulation/helpers/Commands.js
+++ ps/trunk/binaries/data/mods/public/simulation/helpers/Commands.js
@@ -733,11 +733,13 @@
 				continue;
 			}
 
-			var cmpTechnologyManager = QueryOwnerInterface(ent, IID_TechnologyManager);
-			if (cmpUpgrade.GetRequiredTechnology(cmd.template) && !cmpTechnologyManager.IsTechnologyResearched(cmpUpgrade.GetRequiredTechnology(cmd.template)))
+			let cmpTechnologyManager = QueryOwnerInterface(ent, IID_TechnologyManager);
+			let requiredTechnology = cmpUpgrade.GetRequiredTechnology(cmd.template);
+
+			if (requiredTechnology && (!cmpTechnologyManager || !cmpTechnologyManager.IsTechnologyResearched(requiredTechnology)))
 			{
 				if (g_DebugCommands)
-					warn("Invalid command: upgrading requires unresearched technology: " + uneval(cmd));
+					warn("Invalid command: upgrading is not possible for this player or requires unresearched technology: " + uneval(cmd));
 				continue;
 			}