diff --git a/Packaging/Package.appxmanifest b/Packaging/Package.appxmanifest
index 2655d91..cd2fbb7 100644
--- a/Packaging/Package.appxmanifest
+++ b/Packaging/Package.appxmanifest
@@ -9,7 +9,7 @@
   <Identity
     Name="49543SystemTrayMenu.SystemTrayMenu"
     Publisher="CN=5884501C-92ED-45DE-9508-9D987C314243"
-    Version="1.0.21.0" />
+    Version="1.0.22.0" />
 
   <Properties>
     <DisplayName>SystemTrayMenu</DisplayName>
diff --git a/Properties/AssemblyInfo.cs b/Properties/AssemblyInfo.cs
index 1e1fd8a..e6dd7f2 100644
--- a/Properties/AssemblyInfo.cs
+++ b/Properties/AssemblyInfo.cs
@@ -39,5 +39,5 @@ using System.Runtime.InteropServices;
 // You can specify all the values or you can default the Build and Revision Numbers
 // by using the '*' as shown below:
 // [assembly: AssemblyVersion("1.0.*")]
-[assembly: AssemblyVersion("1.0.22.0")]
-[assembly: AssemblyFileVersion("1.0.22.0")]
+[assembly: AssemblyVersion("1.0.22.1")]
+[assembly: AssemblyFileVersion("1.0.22.1")]
diff --git a/Utilities/File/IconReader.cs b/Utilities/File/IconReader.cs
index 6ff009a..f470f25 100644
--- a/Utilities/File/IconReader.cs
+++ b/Utilities/File/IconReader.cs
@@ -25,7 +25,6 @@ namespace SystemTrayMenu.Utilities
         private static readonly ConcurrentDictionary<string, Icon> DictIconCache = new ConcurrentDictionary<string, Icon>();
         private static readonly Icon LoadingIcon = Properties.Resources.Loading;
 
-        // private static readonly object ReadIcon = new object();
         public enum IconSize
         {
             Large = 0, // 32x32 pixels
@@ -38,6 +37,7 @@ namespace SystemTrayMenu.Utilities
             Closed = 1,
         }
 
+        // see https://github.com/Hofknecht/SystemTrayMenu/issues/209.
         public static bool SingleThread { get; set; }
 
         public static void Dispose()
@@ -74,6 +74,8 @@ namespace SystemTrayMenu.Utilities
                 key = extension + linkOverlay;
             }
 
+            ClearBadIcons();
+
             if (!DictIconCache.TryGetValue(key, out Icon icon))
             {
                 icon = LoadingIcon;
@@ -154,6 +156,8 @@ namespace SystemTrayMenu.Utilities
                 key = extension + linkOverlay;
             }
 
+            ClearBadIcons();
+
             if (!DictIconCache.TryGetValue(key, out Icon icon))
             {
                 icon = LoadingIcon;
@@ -210,6 +214,8 @@ namespace SystemTrayMenu.Utilities
 
             string key = path;
 
+            ClearBadIcons();
+
             if (!DictIconCache.TryGetValue(key, out Icon icon))
             {
                 icon = LoadingIcon;
@@ -351,6 +357,21 @@ namespace SystemTrayMenu.Utilities
             return icon;
         }
 
+        /// <summary>
+        /// Clear icons which are null.
+        /// see https://github.com/Hofknecht/SystemTrayMenu/issues/209.
+        /// This only happens with the MainPreload method. SingleThread had only partially solved it before.
+        /// It is unclear exactly where the problem comes from, because it never seems to be null later.
+        /// </summary>
+        private static void ClearBadIcons()
+        {
+            IEnumerable<string> badKeysList = DictIconCache.Where(x => x.Value == null).Select(x => x.Key);
+            foreach (string badKey in badKeysList)
+            {
+                DictIconCache.Remove(badKey, out _);
+            }
+        }
+
         private static bool IsExtensionWithSameIcon(string fileExtension)
         {
             bool isExtensionWithSameIcon = true;