diff --git a/po/colobot.pot b/po/colobot.pot
index 1f183eea..a1446763 100644
--- a/po/colobot.pot
+++ b/po/colobot.pot
@@ -1346,6 +1346,9 @@ msgstr ""
 msgid "Unknown command"
 msgstr ""
 
+msgid "This object is currently busy"
+msgstr ""
+
 msgid "Impossible when flying"
 msgstr ""
 
diff --git a/po/de.po b/po/de.po
index 05a31006..653fa662 100644
--- a/po/de.po
+++ b/po/de.po
@@ -1507,6 +1507,9 @@ msgstr "Dieses Label existiert nicht"
 msgid "This menu is for userlevels from mods, but you didn't install any"
 msgstr ""
 
+msgid "This object is currently busy"
+msgstr ""
+
 msgid "This object is not a member of a class"
 msgstr "Das Objekt ist nicht eine Instanz einer Klasse"
 
diff --git a/po/fr.po b/po/fr.po
index 7eb4e407..6f432671 100644
--- a/po/fr.po
+++ b/po/fr.po
@@ -1479,6 +1479,9 @@ msgstr "Cette étiquette n'existe pas"
 msgid "This menu is for userlevels from mods, but you didn't install any"
 msgstr "Ce menu donne accès aux niveaux spéciaux (importés ou personnalisés), mais aucun n'est installé."
 
+msgid "This object is currently busy"
+msgstr ""
+
 msgid "This object is not a member of a class"
 msgstr "L'objet n'est pas une instance d'une classe"
 
diff --git a/po/pl.po b/po/pl.po
index d9cde920..f17c8176 100644
--- a/po/pl.po
+++ b/po/pl.po
@@ -1481,6 +1481,9 @@ msgstr "Taka etykieta nie istnieje"
 msgid "This menu is for userlevels from mods, but you didn't install any"
 msgstr "To menu jest przeznaczone na poziomy użytkownika z modyfikacji, ale żadne nie są zainstalowane"
 
+msgid "This object is currently busy"
+msgstr "Ten objekt jest obecnie zajęty"
+
 msgid "This object is not a member of a class"
 msgstr "Ten obiekt nie jest członkiem klasy"
 
diff --git a/po/ru.po b/po/ru.po
index 553a4c7e..70727694 100644
--- a/po/ru.po
+++ b/po/ru.po
@@ -1495,6 +1495,9 @@ msgstr "Эта метка не существует"
 msgid "This menu is for userlevels from mods, but you didn't install any"
 msgstr "Это меню для пользовательских уровней из модов, но вы ни одного не уставили"
 
+msgid "This object is currently busy"
+msgstr ""
+
 msgid "This object is not a member of a class"
 msgstr "Этот объект не член класса"
 
diff --git a/src/common/error.h b/src/common/error.h
index d1bdac2a..1ba77b1d 100644
--- a/src/common/error.h
+++ b/src/common/error.h
@@ -31,6 +31,7 @@ enum Error
     ERR_CONTINUE          = 2,        //! <  continues
     ERR_STOP              = 3,        //! <  stops
     ERR_CMD               = 4,        //! <  unknown command
+    ERR_OBJ_BUSY          = 5,        //! <  object is busy
     ERR_MANIP_FLY         = 101,      //! <  impossible in flight
     ERR_MANIP_BUSY        = 102,      //! <  taking: hands already occupied
     ERR_MANIP_NIL         = 103,      //! <  taking: nothing has to take
diff --git a/src/common/restext.cpp b/src/common/restext.cpp
index 859a61f9..5cd6c91a 100644
--- a/src/common/restext.cpp
+++ b/src/common/restext.cpp
@@ -563,6 +563,7 @@ void InitializeRestext()
 
     stringsErr[ERR_UNKNOWN]         = TR("Internal error - tell the developers");
     stringsErr[ERR_CMD]             = TR("Unknown command");
+    stringsErr[ERR_OBJ_BUSY]        = TR("This object is currently busy");
     stringsErr[ERR_MANIP_FLY]       = TR("Impossible when flying");
     stringsErr[ERR_MANIP_BUSY]      = TR("Already carrying something");
     stringsErr[ERR_MANIP_NIL]       = TR("Nothing to grab");
diff --git a/src/object/auto/autodestroyer.cpp b/src/object/auto/autodestroyer.cpp
index 84333f07..deb77ff7 100644
--- a/src/object/auto/autodestroyer.cpp
+++ b/src/object/auto/autodestroyer.cpp
@@ -107,7 +107,7 @@ Error CAutoDestroyer::StartAction(int param)
             m_bExplo   = false;
         }
         else
-            return ERR_UNKNOWN;
+            return ERR_OBJ_BUSY;
     }
     return ERR_OK;
 }
diff --git a/src/object/auto/autofactory.cpp b/src/object/auto/autofactory.cpp
index 17337975..b48e7cf6 100644
--- a/src/object/auto/autofactory.cpp
+++ b/src/object/auto/autofactory.cpp
@@ -129,7 +129,7 @@ Error CAutoFactory::StartAction(int param)
     {
         if ( m_phase != AFP_WAIT )
         {
-            return ERR_OK;
+            return ERR_OBJ_BUSY;
         }
 
         m_type = type;
diff --git a/src/object/auto/autolabo.cpp b/src/object/auto/autolabo.cpp
index 0fb087d5..1cbcbc24 100644
--- a/src/object/auto/autolabo.cpp
+++ b/src/object/auto/autolabo.cpp
@@ -121,7 +121,7 @@ Error CAutoLabo::StartAction(int param)
 {
     if ( m_phase != ALAP_WAIT )
     {
-        return ERR_UNKNOWN;
+        return ERR_OBJ_BUSY;
     }
 
     m_research = static_cast<ResearchType>(param);
diff --git a/src/object/auto/autoresearch.cpp b/src/object/auto/autoresearch.cpp
index 2303d7c9..32380de4 100644
--- a/src/object/auto/autoresearch.cpp
+++ b/src/object/auto/autoresearch.cpp
@@ -104,7 +104,7 @@ Error CAutoResearch::StartAction(int param)
 {
     if ( m_phase != ALP_WAIT )
     {
-        return ERR_UNKNOWN;
+        return ERR_OBJ_BUSY;
     }
 
     m_research = static_cast<ResearchType>(param);