diff --git a/PowerEditor/src/Notepad_plus.cpp b/PowerEditor/src/Notepad_plus.cpp
index 34037b36e..9bdc183b6 100644
--- a/PowerEditor/src/Notepad_plus.cpp
+++ b/PowerEditor/src/Notepad_plus.cpp
@@ -401,7 +401,6 @@ bool Notepad_plus::doOpen(const char *fileName, bool isReadOnly)
 	char longFileName[MAX_PATH];
 	::GetFullPathName(fileName, MAX_PATH, longFileName, NULL);
 
-	//printInt(getCurrentView());
 	if (switchToFile(longFileName))
 	{
 		if (_pTrayIco)
@@ -433,6 +432,15 @@ bool Notepad_plus::doOpen(const char *fileName, bool isReadOnly)
 		}
 	}
 
+	// if file2open matches the ext of user defined session file ext, then it'll be opened as a session
+	char fncp[MAX_PATH];
+	strcpy(fncp, longFileName);
+	char *pExt = PathFindExtension(fncp);
+	const char *definedSessionExt = NppParameters::getInstance()->getNppGUI()._definedSessionExt.c_str();
+	if (strcmp(pExt, definedSessionExt))
+	{
+		return fileLoadSession(longFileName);
+	}
 
 	Utf8_16_Read UnicodeConvertor;
 
@@ -7272,8 +7280,9 @@ void Notepad_plus::getCurrentOpenedFiles(Session & session)
 	_subEditView.activateDocAt(currentDocIndex);
 }
 
-void Notepad_plus::fileLoadSession(const char *fn)
+bool Notepad_plus::fileLoadSession(const char *fn)
 {
+	bool result = false;
 	const char *sessionFileName = NULL;
 	if (fn == NULL)
 	{
@@ -7297,10 +7306,12 @@ void Notepad_plus::fileLoadSession(const char *fn)
 		if ((NppParameters::getInstance())->loadSession(session2Load, sessionFileName))
 		{
 			isAllSuccessful = loadSession(session2Load);
+			result = true;
 		}
 		if (!isAllSuccessful)
 			(NppParameters::getInstance())->writeSession(session2Load, sessionFileName);
 	}
+	return result;
 }
 
 
diff --git a/PowerEditor/src/Notepad_plus.h b/PowerEditor/src/Notepad_plus.h
index 88a9267bf..fceaa3a55 100644
--- a/PowerEditor/src/Notepad_plus.h
+++ b/PowerEditor/src/Notepad_plus.h
@@ -312,7 +312,7 @@ public:
 
 	void getCurrentOpenedFiles(Session & session);
 
-	void fileLoadSession(const char *fn = NULL);
+	bool fileLoadSession(const char *fn = NULL);
 	const char * fileSaveSession(size_t nbFile, char ** fileNames, const char *sessionFile2save);
 	const char * fileSaveSession(size_t nbFile = 0, char ** fileNames = NULL);
 
diff --git a/PowerEditor/src/Parameters.cpp b/PowerEditor/src/Parameters.cpp
index 08901811c..aea802111 100644
--- a/PowerEditor/src/Parameters.cpp
+++ b/PowerEditor/src/Parameters.cpp
@@ -2151,7 +2151,18 @@ void NppParameters::feedGUIParameters(TiXmlNode *node)
 			if (element->Attribute("autoCAction", &i))
 				_nppGUI._autocStatus = (NppGUI::AutocStatus)i;
 		}
+		else if (!strcmp(nm, "sessionExt"))
+		{
+			TiXmlNode *n = childNode->FirstChild();
+			if (n)
+			{
+				val = n->Value();
+				if (val)
+					_nppGUI._definedSessionExt = val;
+			}
+		}
 	}
+
 }
 
 void NppParameters::feedScintillaParam(bool whichOne, TiXmlNode *node)
@@ -2424,6 +2435,7 @@ void NppParameters::writeGUIParams()
 	bool URLExist = false;
 	bool globalOverrideExist = false;
 	bool autocExist = false;
+	bool sessionExtExist = false;
 
 	TiXmlNode *dockingParamNode = NULL;
 
@@ -2606,12 +2618,20 @@ void NppParameters::writeGUIParams()
 			pStr = _nppGUI._globalOverride.enableUnderLine?"yes":"no";
 			element->SetAttribute("underline", pStr);
 		}
-
-		if (!strcmp(nm, "auto-completion"))
+		else if (!strcmp(nm, "auto-completion"))
 		{
 			autocExist = true;
 			element->SetAttribute("autoCAction", _nppGUI._autocStatus);
 		}
+		else if (!strcmp(nm, "sessionExt"))
+		{
+			sessionExtExist = true;
+			TiXmlNode *n = childNode->FirstChild();
+			if (n)
+				n->SetValue(_nppGUI._definedSessionExt.c_str());
+			else
+				childNode->InsertEndChild(TiXmlText(_nppGUI._definedSessionExt.c_str()));
+		}
 	}
 
 	if (!autoDetectionExist)
@@ -2656,6 +2676,7 @@ void NppParameters::writeGUIParams()
 		GUIConfigElement->SetAttribute("name", "langsExcluded");
 		writeExcludedLangList(GUIConfigElement);
 	}
+
 	if (!printSettingExist)
 	{
 		TiXmlElement *GUIConfigElement = (GUIRoot->InsertEndChild(TiXmlElement("GUIConfig")))->ToElement();
@@ -2724,6 +2745,15 @@ void NppParameters::writeGUIParams()
 		// Rase tout
 		GUIRoot->RemoveChild(dockingParamNode);
 	}
+
+	if (!sessionExtExist)
+	{
+		//const char *pStr = bVal?"yes":"no";
+		TiXmlElement *GUIConfigElement = (GUIRoot->InsertEndChild(TiXmlElement("GUIConfig")))->ToElement();
+		GUIConfigElement->SetAttribute("name", "sessionExt");
+		GUIConfigElement->InsertEndChild(TiXmlText(_nppGUI._definedSessionExt.c_str()));
+	}
+
 	insertDockingParamNode(GUIRoot);
 
 }
diff --git a/PowerEditor/src/Parameters.h b/PowerEditor/src/Parameters.h
index d5406af92..781f9e29c 100644
--- a/PowerEditor/src/Parameters.h
+++ b/PowerEditor/src/Parameters.h
@@ -510,7 +510,8 @@ struct NppGUI
 	           _splitterPos(POS_HORIZOTAL), _userDefineDlgStatus(UDD_DOCKED), _tabSize(8),\
 			   _tabReplacedBySpace(false), _fileAutoDetection(cdEnabled), _checkHistoryFiles(true),\
 			   _isMaximized(false), _isMinimizedToTray(false), _rememberLastSession(true), _backup(bak_none), _useDir(false),\
-			   _doTaskList(true), _maitainIndent(true), _saveOpenKeepInSameDir(false), _styleMRU(true), _styleURL(0), _autocStatus(autoc_none) {
+			   _doTaskList(true), _maitainIndent(true), _saveOpenKeepInSameDir(false), _styleMRU(true), _styleURL(0),
+			   _autocStatus(autoc_none), _definedSessionExt("") {
 		_appPos.left = 0;
 		_appPos.top = 0;
 		_appPos.right = 700;
@@ -564,6 +565,7 @@ struct NppGUI
 	GlobalOverride _globalOverride;
 	enum AutocStatus{autoc_none, autoc_func, autoc_word};
 	AutocStatus _autocStatus;
+	string _definedSessionExt;
 };
 
 struct ScintillaViewParams