diff --git a/src/dialog/vfileinfodialog.cpp b/src/dialog/vfileinfodialog.cpp
index 59ad3ed0..40373a87 100644
--- a/src/dialog/vfileinfodialog.cpp
+++ b/src/dialog/vfileinfodialog.cpp
@@ -103,7 +103,8 @@ void VFileInfoDialog::handleInputChanged()
                                           "Please choose another name.")
                                           .arg(g_config->c_warningTextStyle);
             m_warnLabel->setText(nameConflictText);
-        } else if (VUtils::docTypeFromName(name) != m_file->getDocType()) {
+        } else if (m_file->getDocType() != DocType::Unknown
+                   && VUtils::docTypeFromName(name) != m_file->getDocType()) {
             // Check if the name change the doc type.
             nameOk = false;
             showWarnLabel = true;
diff --git a/src/utils/vutils.cpp b/src/utils/vutils.cpp
index 73c186c2..84105465 100644
--- a/src/utils/vutils.cpp
+++ b/src/utils/vutils.cpp
@@ -492,7 +492,7 @@ DocType VUtils::docTypeFromName(const QString &p_name)
         }
     }
 
-    return DocType::Html;
+    return DocType::Unknown;
 }
 
 QString VUtils::generateHtmlTemplate(MarkdownConverterType p_conType, bool p_exportPdf)
diff --git a/src/vconfigmanager.cpp b/src/vconfigmanager.cpp
index eab1199e..32c06aec 100644
--- a/src/vconfigmanager.cpp
+++ b/src/vconfigmanager.cpp
@@ -912,5 +912,9 @@ void VConfigManager::initDocSuffixes()
     container << "co" << "container" << "con";
     m_docSuffixes[(int)DocType::Container] = container;
 
+    QList<QString> html;
+    html << "html";
+    m_docSuffixes[(int)DocType::Html] = html;
+
     qDebug() << "doc suffixes" << m_docSuffixes;
 }
diff --git a/src/vconstants.h b/src/vconstants.h
index 2b21275e..305b7c07 100644
--- a/src/vconstants.h
+++ b/src/vconstants.h
@@ -5,7 +5,7 @@
 // Markdown: Markdown text file;
 // List: Infinite list file like WorkFlowy;
 // Container: a composite file containing multiple files;
-enum class DocType { Html = 0, Markdown, List, Container, Invalid };
+enum class DocType { Html = 0, Markdown, List, Container, Unknown };
 
 // Note: note file managed by VNote;
 // Orphan: external file;
diff --git a/src/veditarea.cpp b/src/veditarea.cpp
index 9c5933f0..9465aa34 100644
--- a/src/veditarea.cpp
+++ b/src/veditarea.cpp
@@ -127,6 +127,13 @@ void VEditArea::openFile(VFile *p_file, OpenFileMode p_mode)
         return;
     }
 
+    // If it is DocType::Unknown, open it using system default method.
+    if (p_file->getDocType() == DocType::Unknown) {
+        QUrl url = QUrl::fromLocalFile(p_file->fetchPath());
+        QDesktopServices::openUrl(url);
+        return;
+    }
+
     // Find if it has been opened already
     int winIdx, tabIdx;
     bool existFile = false;
diff --git a/src/veditarea.h b/src/veditarea.h
index acbd368e..32e6caf7 100644
--- a/src/veditarea.h
+++ b/src/veditarea.h
@@ -27,7 +27,10 @@ class VEditArea : public QWidget, public VNavigationMode
     Q_OBJECT
 public:
     explicit VEditArea(VNote *vnote, QWidget *parent = 0);
+
+    // Whether @p_file has been opened in edit area.
     bool isFileOpened(const VFile *p_file);
+
     bool closeAllFiles(bool p_forced);
     bool closeFile(const VFile *p_file, bool p_forced);
     bool closeFile(const VDirectory *p_dir, bool p_forced);
diff --git a/src/vfilelist.cpp b/src/vfilelist.cpp
index 9fe95ded..e55d0a5b 100644
--- a/src/vfilelist.cpp
+++ b/src/vfilelist.cpp
@@ -117,6 +117,21 @@ void VFileList::initActions()
                 }
             });
 
+    m_openExternalAct = new QAction(tr("Open Via External Program"), this);
+    m_openExternalAct->setToolTip(tr("Open current note via external program"));
+    connect(m_openExternalAct, &QAction::triggered,
+            this, [this]() {
+                QListWidgetItem *item = fileList->currentItem();
+                if (item) {
+                    VNoteFile *file = getVFile(item);
+                    if (file
+                        && (!editArea->isFileOpened(file) || editArea->closeFile(file, false))) {
+                        QUrl url = QUrl::fromLocalFile(file->fetchPath());
+                        QDesktopServices::openUrl(url);
+                    }
+                }
+            });
+
     deleteFileAct = new QAction(QIcon(":/resources/icons/delete_note.svg"),
                                 tr("&Delete"), this);
     deleteFileAct->setToolTip(tr("Delete selected note"));
@@ -221,8 +236,6 @@ void VFileList::fileInfo(VNoteFile *p_file)
             return;
         }
 
-        Q_ASSERT(p_file->getDocType() == VUtils::docTypeFromName(name));
-
         if (!p_file->rename(name)) {
             VUtils::showMessage(QMessageBox::Warning, tr("Warning"),
                                 tr("Fail to rename note <span style=\"%1\">%2</span>.")
@@ -430,9 +443,13 @@ void VFileList::contextMenuRequested(QPoint pos)
 
     if (item && fileList->selectedItems().size() == 1) {
         VNoteFile *file = getVFile(item);
-        if (file && file->getDocType() == DocType::Markdown) {
-            menu.addAction(m_openInReadAct);
-            menu.addAction(m_openInEditAct);
+        if (file) {
+            if (file->getDocType() == DocType::Markdown) {
+                menu.addAction(m_openInReadAct);
+                menu.addAction(m_openInEditAct);
+            }
+
+            menu.addAction(m_openExternalAct);
             menu.addSeparator();
         }
     }
diff --git a/src/vfilelist.h b/src/vfilelist.h
index d73202db..caeca297 100644
--- a/src/vfilelist.h
+++ b/src/vfilelist.h
@@ -106,6 +106,7 @@ private:
     // Actions
     QAction *m_openInReadAct;
     QAction *m_openInEditAct;
+    QAction *m_openExternalAct;
     QAction *newFileAct;
     QAction *deleteFileAct;
     QAction *fileInfoAct;
diff --git a/src/vnotefile.cpp b/src/vnotefile.cpp
index e9c6ad0b..05a05c00 100644
--- a/src/vnotefile.cpp
+++ b/src/vnotefile.cpp
@@ -87,7 +87,10 @@ bool VNoteFile::rename(const QString &p_name)
     }
 
     // Can't not change doc type.
-    Q_ASSERT(m_docType == VUtils::docTypeFromName(m_name));
+    Q_ASSERT(m_docType == DocType::Unknown
+             || m_docType == VUtils::docTypeFromName(m_name));
+
+    m_docType = VUtils::docTypeFromName(m_name);
 
     qDebug() << "file renamed from" << oldName << "to" << m_name;
     return true;