diff --git a/app/build.gradle b/app/build.gradle
index acd7bf3355..bb4e528e1c 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -25,8 +25,8 @@ android {
     defaultConfig {
         resValue "string", "manifest_package_id", "net.gsantner.markor"
         applicationId "net.gsantner.markor"
-        versionName "2.13.0"
-        versionCode 155
+        versionName "2.13.1"
+        versionCode 156
 
         multiDexEnabled true
         minSdkVersion rootProject.ext.version_minSdk
diff --git a/app/src/main/java/net/gsantner/markor/activity/DocumentActivity.java b/app/src/main/java/net/gsantner/markor/activity/DocumentActivity.java
index fd563564b9..4dfc8bc2ed 100644
--- a/app/src/main/java/net/gsantner/markor/activity/DocumentActivity.java
+++ b/app/src/main/java/net/gsantner/markor/activity/DocumentActivity.java
@@ -16,6 +16,7 @@
 import android.os.Build;
 import android.os.Bundle;
 import android.text.Html;
+import android.util.Log;
 import android.view.KeyEvent;
 import android.view.MotionEvent;
 
@@ -95,8 +96,8 @@ private static void launch(
             intent = new Intent(activity, DocumentActivity.class);
 
             if (!(activity instanceof DocumentActivity) &&
-                Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP &&
-                as.isMultiWindowEnabled()
+                    Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP &&
+                    as.isMultiWindowEnabled()
             ) {
                 intent.addFlags(Intent.FLAG_ACTIVITY_NEW_DOCUMENT | Intent.FLAG_ACTIVITY_MULTIPLE_TASK);
             }
@@ -254,7 +255,8 @@ public boolean dispatchTouchEvent(MotionEvent event) {
         }
         try {
             return super.dispatchTouchEvent(event);
-        } catch (IndexOutOfBoundsException ignored) {
+        } catch (Exception e) {
+            Log.e(getClass().getName(), "Error in super.dispatchTouchEvent: " + e);
             return false;
         }
     }
diff --git a/app/src/main/java/net/gsantner/markor/activity/DocumentShareIntoFragment.java b/app/src/main/java/net/gsantner/markor/activity/DocumentShareIntoFragment.java
index 4a688fbb7e..73c1a3e480 100644
--- a/app/src/main/java/net/gsantner/markor/activity/DocumentShareIntoFragment.java
+++ b/app/src/main/java/net/gsantner/markor/activity/DocumentShareIntoFragment.java
@@ -375,7 +375,7 @@ private String formatShare(final String shared) {
             }
 
             // Put the shared text in the right place
-            parts.add(1, shared);
+            parts.add(parts.isEmpty() ? 0 : 1, shared);
 
             return TextUtils.join("", parts);
         }
diff --git a/app/src/main/java/net/gsantner/markor/frontend/textview/HighlightingEditor.java b/app/src/main/java/net/gsantner/markor/frontend/textview/HighlightingEditor.java
index 39a452ecfa..f29d2eed17 100644
--- a/app/src/main/java/net/gsantner/markor/frontend/textview/HighlightingEditor.java
+++ b/app/src/main/java/net/gsantner/markor/frontend/textview/HighlightingEditor.java
@@ -18,10 +18,12 @@
 import android.text.Layout;
 import android.text.TextWatcher;
 import android.util.AttributeSet;
+import android.util.Log;
 import android.view.KeyEvent;
 import android.view.View;
 import android.view.ViewTreeObserver;
 import android.view.accessibility.AccessibilityEvent;
+import android.widget.Toast;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.RequiresApi;
@@ -37,6 +39,7 @@
 
 import java.util.Objects;
 import java.util.concurrent.ExecutorService;
+import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.SynchronousQueue;
 import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
@@ -118,6 +121,13 @@ public boolean onPreDraw() {
     @Override
     protected void onDraw(Canvas canvas) {
         super.onDraw(canvas);
+        try {
+            super.onDraw(canvas);
+        } catch (Exception e) {
+            // Hinder drawing from crashing the app
+            Log.e(getClass().getName(), "HighlightingEdtior onDraw->super.onDraw crash" + e);
+            Toast.makeText(getContext(), e.toString(), Toast.LENGTH_SHORT).show();
+        }
     }
 
     // Highlighting
@@ -173,7 +183,10 @@ public void recomputeHighlighting() {
      */
     private void recomputeHighlightingAsync() {
         if (runHighlight(true)) {
-            executor.execute(this::_recomputeHighlightingWorker);
+            try {
+                executor.execute(this::_recomputeHighlightingWorker);
+            } catch (RejectedExecutionException ignored) {
+            }
         }
     }
 
@@ -262,14 +275,12 @@ public boolean bringPointIntoView(int i) {
 
     private int rowStart(final int y) {
         final Layout layout = getLayout();
-        final int line = layout.getLineForVertical(y);
-        return layout.getLineStart(line);
+        return layout == null ? 0 : layout.getLineStart(layout.getLineForVertical(y));
     }
 
     private int rowEnd(final int y) {
         final Layout layout = getLayout();
-        final int line = layout.getLineForVertical(y);
-        return layout.getLineEnd(line);
+        return layout == null ? 0 : layout.getLineEnd(layout.getLineForVertical(y));
     }
 
     // Text-Casing
@@ -371,7 +382,12 @@ public boolean onTextContextMenuItem(int id) {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M && id == android.R.id.paste) {
             id = android.R.id.pasteAsPlainText;
         }
-        return super.onTextContextMenuItem(id);
+        try {
+            // i.e. DeadSystemRuntimeException can happen here
+            return super.onTextContextMenuItem(id);
+        } catch (Exception ignored) {
+            return true;
+        }
     }
 
     // Accessibility code is blocked during rapid update events
diff --git a/app/src/main/java/net/gsantner/markor/model/AppSettings.java b/app/src/main/java/net/gsantner/markor/model/AppSettings.java
index 7c83c5095f..f354681012 100644
--- a/app/src/main/java/net/gsantner/markor/model/AppSettings.java
+++ b/app/src/main/java/net/gsantner/markor/model/AppSettings.java
@@ -855,7 +855,7 @@ public boolean isExperimentalFeaturesEnabled() {
     }
 
     public boolean isHighlightBiggerHeadings() {
-        return getBool(R.string.pref_key__editor_markdown_bigger_headings_2, false);
+        return getBool(R.string.pref_key__editor_markdown_bigger_headings_3, false);
     }
 
     public String getViewModeLinkColor() {
diff --git a/app/src/main/java/net/gsantner/opoc/frontend/filebrowser/GsFileBrowserListAdapter.java b/app/src/main/java/net/gsantner/opoc/frontend/filebrowser/GsFileBrowserListAdapter.java
index d0b030c9fc..8cccb29124 100644
--- a/app/src/main/java/net/gsantner/opoc/frontend/filebrowser/GsFileBrowserListAdapter.java
+++ b/app/src/main/java/net/gsantner/opoc/frontend/filebrowser/GsFileBrowserListAdapter.java
@@ -151,7 +151,7 @@ public Map<File, File> getVirtualFolders() {
         }
 
         for (final File file : ContextCompat.getExternalFilesDirs(_context, null)) {
-            if (file == null || file.getParentFile() == null) {
+            if (file == null || (file != null && file.getParentFile() == null)) {
                 continue;
             }
             final File remap = new File(VIRTUAL_STORAGE_ROOT, "AppData (" + file.getParentFile().toString().replace("/", "-").substring(1) + ")");
diff --git a/app/src/main/java/net/gsantner/opoc/frontend/textview/TextViewUndoRedo.java b/app/src/main/java/net/gsantner/opoc/frontend/textview/TextViewUndoRedo.java
index 9a4f6c254b..f90325092f 100644
--- a/app/src/main/java/net/gsantner/opoc/frontend/textview/TextViewUndoRedo.java
+++ b/app/src/main/java/net/gsantner/opoc/frontend/textview/TextViewUndoRedo.java
@@ -43,7 +43,9 @@ public void onClick(View v) {
 import android.text.Selection;
 import android.text.TextWatcher;
 import android.text.style.UnderlineSpan;
+import android.util.Log;
 import android.widget.TextView;
+import android.widget.Toast;
 
 import net.gsantner.markor.frontend.textview.TextViewUtils;
 
@@ -150,8 +152,10 @@ public void undo() {
         mIsUndoOrRedo = true;
         try {
             text.replace(start, end, edit.before);
-        } catch (Exception ex){
+        } catch (Exception ex) {
             // In case a undo would crash the app, don't do it instead
+            Log.e(getClass().getName(), "undo() Error in text.replace" + ex);
+            Toast.makeText(mTextView.getContext(), "undo() Error in text.replace" + ex, Toast.LENGTH_LONG).show();
             return;
         }
         mIsUndoOrRedo = false;
diff --git a/app/src/main/java/net/gsantner/opoc/util/GsContextUtils.java b/app/src/main/java/net/gsantner/opoc/util/GsContextUtils.java
index c243af4224..7bff4dad0c 100644
--- a/app/src/main/java/net/gsantner/opoc/util/GsContextUtils.java
+++ b/app/src/main/java/net/gsantner/opoc/util/GsContextUtils.java
@@ -1861,7 +1861,7 @@ public void extractResultFromActivityResult(final Activity context, final int re
                 if (resultCode == Activity.RESULT_OK && intent != null && intent.getData() != null) {
                     final Uri uri = intent.getData();
                     final String uriPath = uri.getPath();
-                    final String ext = uriPath.substring(uriPath.lastIndexOf("."));
+                    final String ext = uriPath == null || !uriPath.contains(".") ? "" : uriPath.substring(uriPath.lastIndexOf("."));
                     final String datestr = new SimpleDateFormat("yyyy-MM-dd'T'HH-mm-ss", Locale.ENGLISH).format(new Date());
                     final File temp = new File(context.getCacheDir(), datestr + ext);
                     GsFileUtils.copyUriToFile(context, uri, temp);
@@ -2743,12 +2743,12 @@ public void dialogFullWidth(AlertDialog dialog, boolean fullWidth, boolean showK
     }
 
     public static void windowAspectRatio(
-        final Window window,
-        final DisplayMetrics displayMetrics,
-        float portraitWidthRatio,
-        float portraitHeightRatio,
-        float landscapeWidthRatio,
-        float landscapeHeightRatio
+            final Window window,
+            final DisplayMetrics displayMetrics,
+            float portraitWidthRatio,
+            float portraitHeightRatio,
+            float landscapeWidthRatio,
+            float landscapeHeightRatio
     ) {
         if (window == null) {
             return;
diff --git a/app/src/main/res/values/string-not_translatable.xml b/app/src/main/res/values/string-not_translatable.xml
index b94b958639..1c54aad0aa 100644
--- a/app/src/main/res/values/string-not_translatable.xml
+++ b/app/src/main/res/values/string-not_translatable.xml
@@ -180,7 +180,7 @@ work. If not, see <https://creativecommons.org/publicdomain/zero/1.0/>.
     <string name="pref_key__editor_disable_spelling_red_underline" translatable="false">pref_key__editor_disable_spelling_red_underline</string>
     <string name="pref_key__highlight_code_monospace_font" translatable="false">pref_key__highlight_code_monospace_font</string>
     <string name="pref_key__highlight_code_block_disabled" translatable="false">pref_key__highlight_code_block_disabled</string>
-    <string name="pref_key__editor_markdown_bigger_headings_2" translatable="false">pref_key__editor_markdown_bigger_headings_2</string>
+    <string name="pref_key__editor_markdown_bigger_headings_3" translatable="false">pref_key__editor_markdown_bigger_headings_3</string>
     <string name="pref_key__editor_unordered_list_character" translatable="false">pref_key__editor_unordered_list_character</string>
     <string name="pref_key__recent_documents" translatable="false">pref_key__recent_documents</string>
     <string name="pref_key__popular_documents" translatable="false">pref_key__popular_documents</string>
diff --git a/app/src/main/res/xml/preferences_master.xml b/app/src/main/res/xml/preferences_master.xml
index 8fc6e6e26d..dbc0522597 100644
--- a/app/src/main/res/xml/preferences_master.xml
+++ b/app/src/main/res/xml/preferences_master.xml
@@ -340,7 +340,7 @@
             <CheckBoxPreference
                 android:defaultValue="false"
                 android:icon="@drawable/ic_format_size_black_24dp"
-                android:key="@string/pref_key__editor_markdown_bigger_headings_2"
+                android:key="@string/pref_key__editor_markdown_bigger_headings_3"
                 android:summary="@string/increase_text_size_of_headings_according_to_level"
                 android:title="@string/bigger_headings" />
         </PreferenceCategory>
diff --git a/metadata/en-US/full_description.txt b/metadata/en-US/full_description.txt
index b4221a5c9c..7266c8c513 100644
--- a/metadata/en-US/full_description.txt
+++ b/metadata/en-US/full_description.txt
@@ -17,9 +17,9 @@
 👌 No ads or unnecessary permissions
 🌎 Language selection -- use other language than on the system
 
-💡 Unlike other office suites (like <a href="fdroid.app:org.documentfoundation.libreoffice">LibreOffice</a>) or to-do apps (like Wunderlist), Markor has one streamlined text editor with no other editing UI. Markor shows how powerful and expressive simple text can be. View, edit, manipulate and convert plaintext!
+💡 Unlike other office suites (like <a href="https://f-droid.org/packages/org.documentfoundation.libreoffice/">LibreOffice</a>) or to-do apps (like Wunderlist), Markor has one streamlined text editor with no other editing UI. Markor shows how powerful and expressive simple text can be. View, edit, manipulate and convert plaintext!
 
-🔃 Markor works with sync apps, but they have to do syncing respectively. Sync clients known to work in combination include BitTorrent Sync, Dropbox, FolderSync, <a href="fdroid.app:com.owncloud.android">OwnCloud</a>, <a href="fdroid.app:com.nextcloud.client">NextCloud</a>, <a href="fdroid.app:com.seafile.seadroid2">Seafile</a>, <a href="fdroid.app:com.nutomic.syncthingandroid">Syncthing</a>, <a href="fdroid.app:org.amoradi.syncopoli">Syncopoli</a>
+🔃 Markor works with sync apps, but they have to do syncing respectively. Sync clients known to work in combination include BitTorrent Sync, Dropbox, FolderSync, <a href="https://f-droid.org/packages/com.owncloud.android/">OwnCloud</a>, <a href="https://f-droid.org/packages/com.nextcloud.client/">NextCloud</a>, <a href="https://f-droid.org/packages/com.seafile.seadroid2/">Seafile</a>, <a href="https://f-droid.org/packages/com.nutomic.syncthingandroid/">Syncthing</a>, <a href="https://f-droid.org/packages/org.amoradi.syncopoli/">Syncopoli</a>
 
 👀 These apps may also be in your interest if you like Markor: OneNote, EverNote, Google Keep, Wunderlist, Read-It-Later, Pocket, Epsilon Notes, iA Writer, Todoist, Shaarli, Wallabag, Simple Notes, Simpletask, Share to clipboard, NextCloud Bookmarks, Easy Open Link