diff --git a/dotnet-examples/offline-decode-files/Program.cs b/dotnet-examples/offline-decode-files/Program.cs
index 301774f8e..9e0dd792c 100644
--- a/dotnet-examples/offline-decode-files/Program.cs
+++ b/dotnet-examples/offline-decode-files/Program.cs
@@ -17,75 +17,74 @@ class Options
   {
 
     [Option("sample-rate", Required = false, Default = 16000, HelpText = "Sample rate of the data used to train the model")]
-    public int SampleRate { get; set; }
+    public int SampleRate { get; set; }  = 16000;
 
     [Option("feat-dim", Required = false, Default = 80, HelpText = "Dimension of the features used to train the model")]
-    public int FeatureDim { get; set; }
+    public int FeatureDim { get; set; } = 80;
 
     [Option(Required = false, HelpText = "Path to tokens.txt")]
-    public string Tokens { get; set; }
+    public string Tokens { get; set; } = "";
 
     [Option(Required = false, Default = "", HelpText = "Path to transducer encoder.onnx. Used only for transducer models")]
-    public string Encoder { get; set; }
+    public string Encoder { get; set; } = "";
 
     [Option(Required = false, Default = "", HelpText = "Path to transducer decoder.onnx. Used only for transducer models")]
-    public string Decoder { get; set; }
+    public string Decoder { get; set; } = "";
 
     [Option(Required = false,  Default = "",HelpText = "Path to transducer joiner.onnx. Used only for transducer models")]
-    public string Joiner { get; set; }
+    public string Joiner { get; set; } = "";
 
     [Option("model-type", Required = false, Default = "", HelpText = "model type")]
-    public string ModelType { get; set; }
+    public string ModelType { get; set; } = "";
 
     [Option("whisper-encoder", Required = false, Default = "", HelpText = "Path to whisper encoder.onnx. Used only for whisper models")]
-    public string WhisperEncoder { get; set; }
+    public string WhisperEncoder { get; set; } = "";
 
     [Option("whisper-decoder", Required = false, Default = "", HelpText = "Path to whisper decoder.onnx. Used only for whisper models")]
-    public string WhisperDecoder { get; set; }
+    public string WhisperDecoder { get; set; } = "";
 
     [Option("whisper-language", Required = false, Default = "", HelpText = "Language of the input file. Can be empty")]
-    public string WhisperLanguage{ get; set; }
+    public string WhisperLanguage{ get; set; } = "";
 
     [Option("whisper-task", Required = false, Default = "transcribe", HelpText = "transcribe or translate")]
-    public string WhisperTask{ get; set; }
+    public string WhisperTask{ get; set; } = "transcribe";
 
     [Option("tdnn-model", Required = false, Default = "", HelpText = "Path to tdnn yesno model")]
-    public string TdnnModel { get; set; }
-
+    public string TdnnModel { get; set; } = "";
 
     [Option(Required = false, HelpText = "Path to model.onnx. Used only for paraformer models")]
-    public string Paraformer { get; set; }
+    public string Paraformer { get; set; } = "";
 
     [Option("nemo-ctc", Required = false, HelpText = "Path to model.onnx. Used only for NeMo CTC models")]
-    public string NeMoCtc { get; set; }
+    public string NeMoCtc { get; set; } = "";
 
     [Option("telespeech-ctc", Required = false, HelpText = "Path to model.onnx. Used only for TeleSpeech CTC models")]
-    public string TeleSpeechCtc { get; set; }
+    public string TeleSpeechCtc { get; set; } = "";
 
     [Option("num-threads", Required = false, Default = 1, HelpText = "Number of threads for computation")]
-    public int NumThreads { get; set; }
+    public int NumThreads { get; set; } = 1;
 
     [Option("decoding-method", Required = false, Default = "greedy_search",
             HelpText = "Valid decoding methods are: greedy_search, modified_beam_search")]
-    public string DecodingMethod { get; set; }
+    public string DecodingMethod { get; set; } = "greedy_search";
 
     [Option("rule-fsts", Required = false, Default = "",
             HelpText = "If not empty, path to rule fst for inverse text normalization")]
-    public string RuleFsts { get; set; }
+    public string RuleFsts { get; set; } = "";
 
     [Option("max-active-paths", Required = false, Default = 4,
         HelpText = @"Used only when --decoding--method is modified_beam_search.
 It specifies number of active paths to keep during the search")]
-    public int MaxActivePaths { get; set; }
+    public int MaxActivePaths { get; set; } = 4;
 
     [Option("hotwords-file", Required = false, Default = "", HelpText = "Path to hotwords.txt")]
-    public string HotwordsFile { get; set; }
+    public string HotwordsFile { get; set; } = "";
 
     [Option("hotwords-score", Required = false, Default = 1.5F, HelpText = "hotwords score")]
-    public float HotwordsScore { get; set; }
+    public float HotwordsScore { get; set; } = 1.5F;
 
     [Option("files", Required = true, HelpText = "Audio files for decoding")]
-    public IEnumerable<string> Files { get; set; }
+    public IEnumerable<string> Files { get; set; } = new string[] {};
   }
 
   static void Main(string[] args)
diff --git a/dotnet-examples/offline-tts/Program.cs b/dotnet-examples/offline-tts/Program.cs
index a3fbe2afd..6216095f4 100644
--- a/dotnet-examples/offline-tts/Program.cs
+++ b/dotnet-examples/offline-tts/Program.cs
@@ -18,49 +18,49 @@ class Options
   {
 
     [Option("tts-rule-fsts", Required = false, Default = "", HelpText = "path to rule.fst")]
-    public string RuleFsts { get; set; }
+    public string RuleFsts { get; set; } = "";
 
     [Option("tts-rule-fars", Required = false, Default = "", HelpText = "path to rule.far")]
-    public string RuleFars { get; set; }
+    public string RuleFars { get; set; } = "";
 
     [Option("vits-dict-dir", Required = false, Default = "", HelpText = "Path to the directory containing dict for jieba.")]
-    public string DictDir { get; set; }
+    public string DictDir { get; set; } = "";
 
     [Option("vits-data-dir", Required = false, Default = "", HelpText = "Path to the directory containing dict for espeak-ng.")]
-    public string DataDir { get; set; }
+    public string DataDir { get; set; } = "";
 
     [Option("vits-length-scale", Required = false, Default = 1, HelpText = "speech speed. Larger->Slower; Smaller->faster")]
-    public float LengthScale { get; set; }
+    public float LengthScale { get; set; } = 1;
 
     [Option("vits-noise-scale", Required = false, Default = 0.667f, HelpText = "noise_scale for VITS models")]
-    public float NoiseScale { get; set; }
+    public float NoiseScale { get; set; } = 0.667F;
 
-    [Option("vits-noise-scale-w", Required = false, Default = 0.8f, HelpText = "noise_scale_w for VITS models")]
-    public float NoiseScaleW { get; set; }
+    [Option("vits-noise-scale-w", Required = false, Default = 0.8F, HelpText = "noise_scale_w for VITS models")]
+    public float NoiseScaleW { get; set; } = 0.8F;
 
     [Option("vits-lexicon", Required = false, Default = "", HelpText = "Path to lexicon.txt")]
-    public string Lexicon { get; set; }
+    public string Lexicon { get; set; } = "";
 
     [Option("vits-tokens", Required = false, Default = "", HelpText = "Path to tokens.txt")]
-    public string Tokens { get; set; }
+    public string Tokens { get; set; } = "";
 
     [Option("tts-max-num-sentences", Required = false, Default = 1, HelpText = "Maximum number of sentences that we process at a time.")]
-    public int MaxNumSentences { get; set; }
+    public int MaxNumSentences { get; set; } = 1;
 
     [Option(Required = false, Default = 0, HelpText = "1 to show debug messages.")]
-    public int Debug { get; set; }
+    public int Debug { get; set; } = 0;
 
     [Option("vits-model", Required = true, HelpText = "Path to VITS model")]
-    public string Model { get; set; }
+    public string Model { get; set; } = "";
 
     [Option("sid", Required = false, Default = 0, HelpText = "Speaker ID")]
-    public int SpeakerId { get; set; }
+    public int SpeakerId { get; set; } = 0;
 
     [Option("text", Required = true, HelpText = "Text to synthesize")]
-    public string Text { get; set; }
+    public string Text { get; set; } = "";
 
     [Option("output-filename", Required = true, Default = "./generated.wav", HelpText = "Path to save the generated audio")]
-    public string OutputFilename { get; set; }
+    public string OutputFilename { get; set; } = "./generated.wav";
   }
 
   static void Main(string[] args)
diff --git a/dotnet-examples/online-decode-files/Program.cs b/dotnet-examples/online-decode-files/Program.cs
index 3e8ee93e8..ad53624de 100644
--- a/dotnet-examples/online-decode-files/Program.cs
+++ b/dotnet-examples/online-decode-files/Program.cs
@@ -18,81 +18,80 @@ class OnlineDecodeFiles
   class Options
   {
     [Option(Required = true, HelpText = "Path to tokens.txt")]
-    public string Tokens { get; set; }
+    public string Tokens { get; set; } = "";
 
     [Option(Required = false, Default = "cpu", HelpText = "Provider, e.g., cpu, coreml")]
-    public string Provider { get; set; }
+    public string Provider { get; set; } = "";
 
     [Option(Required = false, HelpText = "Path to transducer encoder.onnx")]
-    public string Encoder { get; set; }
+    public string Encoder { get; set; } = "";
 
     [Option(Required = false, HelpText = "Path to transducer decoder.onnx")]
-    public string Decoder { get; set; }
+    public string Decoder { get; set; } = "";
 
     [Option(Required = false, HelpText = "Path to transducer joiner.onnx")]
-    public string Joiner { get; set; }
+    public string Joiner { get; set; } = "";
 
     [Option("paraformer-encoder", Required = false, HelpText = "Path to paraformer encoder.onnx")]
-    public string ParaformerEncoder { get; set; }
+    public string ParaformerEncoder { get; set; } = "";
 
     [Option("paraformer-decoder", Required = false, HelpText = "Path to paraformer decoder.onnx")]
-    public string ParaformerDecoder { get; set; }
+    public string ParaformerDecoder { get; set; } = "";
 
     [Option("zipformer2-ctc", Required = false, HelpText = "Path to zipformer2 CTC onnx model")]
-    public string Zipformer2Ctc { get; set; }
+    public string Zipformer2Ctc { get; set; } = "";
 
     [Option("num-threads", Required = false, Default = 1, HelpText = "Number of threads for computation")]
-    public int NumThreads { get; set; }
+    public int NumThreads { get; set; } = 1;
 
     [Option("decoding-method", Required = false, Default = "greedy_search",
             HelpText = "Valid decoding methods are: greedy_search, modified_beam_search")]
-    public string DecodingMethod { get; set; }
+    public string DecodingMethod { get; set; } = "greedy_search";
 
     [Option(Required = false, Default = false, HelpText = "True to show model info during loading")]
-    public bool Debug { get; set; }
+    public bool Debug { get; set; } = false;
 
     [Option("sample-rate", Required = false, Default = 16000, HelpText = "Sample rate of the data used to train the model")]
-    public int SampleRate { get; set; }
+    public int SampleRate { get; set; } = 16000;
 
     [Option("max-active-paths", Required = false, Default = 4,
         HelpText = @"Used only when --decoding--method is modified_beam_search.
 It specifies number of active paths to keep during the search")]
-    public int MaxActivePaths { get; set; }
+    public int MaxActivePaths { get; set; } = 4;
 
     [Option("enable-endpoint", Required = false, Default = false,
         HelpText = "True to enable endpoint detection.")]
-    public bool EnableEndpoint { get; set; }
+    public bool EnableEndpoint { get; set; } = false;
 
     [Option("rule1-min-trailing-silence", Required = false, Default = 2.4F,
         HelpText = @"An endpoint is detected if trailing silence in seconds is
 larger than this value even if nothing has been decoded. Used only when --enable-endpoint is true.")]
-    public float Rule1MinTrailingSilence { get; set; }
+    public float Rule1MinTrailingSilence { get; set; } = 2.4F;
 
     [Option("rule2-min-trailing-silence", Required = false, Default = 1.2F,
         HelpText = @"An endpoint is detected if trailing silence in seconds is
 larger than this value after something that is not blank has been decoded. Used
 only when --enable-endpoint is true.")]
-    public float Rule2MinTrailingSilence { get; set; }
+    public float Rule2MinTrailingSilence { get; set; }  = 1.2F;
 
     [Option("rule3-min-utterance-length", Required = false, Default = 20.0F,
         HelpText = @"An endpoint is detected if the utterance in seconds is
 larger than this value. Used only when --enable-endpoint is true.")]
-    public float Rule3MinUtteranceLength { get; set; }
+    public float Rule3MinUtteranceLength { get; set; } = 20.0F;
 
     [Option("hotwords-file", Required = false, Default = "", HelpText = "Path to hotwords.txt")]
-    public string HotwordsFile { get; set; }
+    public string HotwordsFile { get; set; } = "";
 
     [Option("hotwords-score", Required = false, Default = 1.5F, HelpText = "hotwords score")]
-    public float HotwordsScore { get; set; }
+    public float HotwordsScore { get; set; } = 1.5F;
 
     [Option("rule-fsts", Required = false, Default = "",
             HelpText = "If not empty, path to rule fst for inverse text normalization")]
-    public string RuleFsts { get; set; }
+    public string RuleFsts { get; set; } = "";
 
 
     [Option("files", Required = true, HelpText = "Audio files for decoding")]
-    public IEnumerable<string> Files { get; set; }
-
+    public IEnumerable<string> Files { get; set; } = new string[] {};
   }
 
   static void Main(string[] args)
diff --git a/scripts/dotnet/OfflineRecognizer.cs b/scripts/dotnet/OfflineRecognizer.cs
index 1acda5dfd..761b5dbfb 100644
--- a/scripts/dotnet/OfflineRecognizer.cs
+++ b/scripts/dotnet/OfflineRecognizer.cs
@@ -2,7 +2,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using System.Runtime.InteropServices;
 
 namespace SherpaOnnx
@@ -29,7 +28,14 @@ public void Decode(OfflineStream stream)
         // The caller should ensure all passed streams are ready for decoding.
         public void Decode(IEnumerable<OfflineStream> streams)
         {
-            IntPtr[] ptrs = streams.Select(s => s.Handle).ToArray();
+            // TargetFramework=net20 does not support System.Linq
+            // IntPtr[] ptrs = streams.Select(s => s.Handle).ToArray();
+            List<IntPtr> list = new List<IntPtr>();
+            foreach (OfflineStream s in streams)
+            {
+              list.Add(s.Handle);
+            }
+            IntPtr[] ptrs = list.ToArray();
             Decode(_handle.Handle, ptrs, ptrs.Length);
         }
 
diff --git a/scripts/dotnet/OnlineRecognizer.cs b/scripts/dotnet/OnlineRecognizer.cs
index f2b7cdea8..48a2c92b9 100644
--- a/scripts/dotnet/OnlineRecognizer.cs
+++ b/scripts/dotnet/OnlineRecognizer.cs
@@ -3,7 +3,6 @@
 /// Copyright (c)  2024.5 by 东风破
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using System.Runtime.InteropServices;
 
 namespace SherpaOnnx
@@ -49,7 +48,15 @@ public void Decode(OnlineStream stream)
         // The caller should ensure all passed streams are ready for decoding.
         public void Decode(IEnumerable<OnlineStream> streams)
         {
-            IntPtr[] ptrs = streams.Select(s => s.Handle).ToArray();
+            // TargetFramework=net20 does not support System.Linq
+            // IntPtr[] ptrs = streams.Select(s => s.Handle).ToArray();
+            List<IntPtr> list = new List<IntPtr>();
+            foreach (OnlineStream s in streams)
+            {
+              list.Add(s.Handle);
+            }
+
+            IntPtr[] ptrs = list.ToArray();
             Decode(_handle.Handle, ptrs, ptrs.Length);
         }
 
diff --git a/scripts/dotnet/OnlineRecognizerResult.cs b/scripts/dotnet/OnlineRecognizerResult.cs
index d13fb0cc0..328653ee5 100644
--- a/scripts/dotnet/OnlineRecognizerResult.cs
+++ b/scripts/dotnet/OnlineRecognizerResult.cs
@@ -77,7 +77,7 @@ public OnlineRecognizerResult(IntPtr handle)
                 }
                 else
                 {
-                    _timestamps = Array.Empty<float>();
+                    _timestamps = new float[] {};
                 }
             }
         }
diff --git a/scripts/dotnet/run.sh b/scripts/dotnet/run.sh
index 4b6d2bf00..8beb8f34d 100755
--- a/scripts/dotnet/run.sh
+++ b/scripts/dotnet/run.sh
@@ -38,7 +38,7 @@ macos_arm64_wheel=$src_dir/$macos_arm64_wheel_filename
 windows_x64_wheel_filename=sherpa_onnx-${SHERPA_ONNX_VERSION}-cp38-cp38-win_amd64.whl
 windows_x64_wheel=$src_dir/$windows_x64_wheel_filename
 
-windows_x86_wheel_filename=sherpa_onnx-${SHERPA_ONNX_VERSION}-cp38-cp38-win32.whl
+windows_x86_wheel_filename=sherpa-onnx-${SHERPA_ONNX_VERSION}-win-x86.tar.bz2
 windows_x86_wheel=$src_dir/$windows_x86_wheel_filename
 
 windows_arm64_wheel_filename=sherpa-onnx-${SHERPA_ONNX_VERSION}-win-arm64.tar.bz2
@@ -138,10 +138,10 @@ if [ ! -f $src_dir/windows-x86/sherpa-onnx-core.dll ]; then
   if [ -f $windows_x86_wheel ]; then
     cp -v $windows_x86_wheel .
   else
-    curl -OL https://$HF_MIRROR/csukuangfj/sherpa-onnx-wheels/resolve/main/$windows_x86_wheel_filename
+    curl -OL https://$HF_MIRROR/csukuangfj/sherpa-onnx-libs/resolve/main/windows-for-dotnet/$windows_x86_wheel_filename
   fi
-  unzip $windows_x86_wheel_filename
-  cp -v sherpa_onnx-${SHERPA_ONNX_VERSION}.data/data/bin/*.dll ../
+  tar xvf $windows_x86_wheel_filename
+  cp -v sherpa-onnx-${SHERPA_ONNX_VERSION}-win-x86/*dll ../
   cd ..
 
   rm -rf wheel
@@ -159,7 +159,7 @@ if [ ! -f $src_dir/windows-arm64/sherpa-onnx-core.dll ]; then
   else
     curl -OL https://$HF_MIRROR/csukuangfj/sherpa-onnx-libs/resolve/main/windows-for-dotnet/$windows_arm64_wheel_filename
   fi
-  unzip $windows_arm64_wheel_filename
+  tar xvf $windows_arm64_wheel_filename
   cp -v sherpa-onnx-${SHERPA_ONNX_VERSION}-win-arm64/*dll ../
   cd ..
 
diff --git a/scripts/dotnet/sherpa-onnx.csproj.in b/scripts/dotnet/sherpa-onnx.csproj.in
index 25a2b5c1f..b155c60fe 100644
--- a/scripts/dotnet/sherpa-onnx.csproj.in
+++ b/scripts/dotnet/sherpa-onnx.csproj.in
@@ -4,7 +4,7 @@
     <PackageReadmeFile>README.md</PackageReadmeFile>
     <OutputType>Library</OutputType>
     <LangVersion>10.0</LangVersion>
-    <TargetFrameworks>netstandard2.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net45;net40;net35;net20;netstandard2.0</TargetFrameworks>
     <RuntimeIdentifiers>linux-x64;osx-x64;osx-arm64;win-x64;win-x86;win-arm64</RuntimeIdentifiers>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <AssemblyName>sherpa-onnx</AssemblyName>
diff --git a/scripts/dotnet/sherpa-onnx.csproj.runtime.in b/scripts/dotnet/sherpa-onnx.csproj.runtime.in
index f90ae2c3c..2a387ccea 100644
--- a/scripts/dotnet/sherpa-onnx.csproj.runtime.in
+++ b/scripts/dotnet/sherpa-onnx.csproj.runtime.in
@@ -3,7 +3,7 @@
     <PackageLicenseExpression>Apache-2.0</PackageLicenseExpression>
     <PackageReadmeFile>README.md</PackageReadmeFile>
     <OutputType>Library</OutputType>
-    <TargetFrameworks>netstandard2.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net45;net40;net35;net20;netstandard2.0</TargetFrameworks>
     <RuntimeIdentifier>{{ dotnet_rid }}</RuntimeIdentifier>
     <AssemblyName>sherpa-onnx</AssemblyName>
     <Version>{{ version }}</Version>
diff --git a/sherpa-onnx/kotlin-api/OfflineRecognizer.kt b/sherpa-onnx/kotlin-api/OfflineRecognizer.kt
index fdf91a6d6..e5f1547d3 100644
--- a/sherpa-onnx/kotlin-api/OfflineRecognizer.kt
+++ b/sherpa-onnx/kotlin-api/OfflineRecognizer.kt
@@ -171,7 +171,7 @@ fun getOfflineModelConfig(type: Int): OfflineModelConfig? {
                     joiner = "$modelDir/joiner-epoch-30-avg-4.onnx",
                 ),
                 tokens = "$modelDir/tokens.txt",
-                modelType = "zipformer",
+                modelType = "transducer",
             )
         }
 
@@ -209,7 +209,7 @@ fun getOfflineModelConfig(type: Int): OfflineModelConfig? {
                     joiner = "$modelDir/joiner-epoch-12-avg-4.int8.onnx",
                 ),
                 tokens = "$modelDir/tokens.txt",
-                modelType = "zipformer",
+                modelType = "transducer",
             )
         }
 
@@ -222,7 +222,7 @@ fun getOfflineModelConfig(type: Int): OfflineModelConfig? {
                     joiner = "$modelDir/joiner-epoch-20-avg-1.int8.onnx",
                 ),
                 tokens = "$modelDir/tokens.txt",
-                modelType = "zipformer2",
+                modelType = "transducer",
             )
         }
 
@@ -281,7 +281,7 @@ fun getOfflineModelConfig(type: Int): OfflineModelConfig? {
             return OfflineModelConfig(
                 teleSpeech = "$modelDir/model.int8.onnx",
                 tokens = "$modelDir/tokens.txt",
-                modelType = "tele_speech",
+                modelType = "telespeech_ctc",
             )
         }
 
@@ -294,7 +294,7 @@ fun getOfflineModelConfig(type: Int): OfflineModelConfig? {
                     joiner = "$modelDir/joiner-epoch-12-avg-5.int8.onnx",
                 ),
                 tokens = "$modelDir/tokens.txt",
-                modelType = "zipformer2",
+                modelType = "transducer",
             )
         }
 
@@ -307,7 +307,7 @@ fun getOfflineModelConfig(type: Int): OfflineModelConfig? {
                     joiner = "$modelDir/joiner-epoch-99-avg-1.int8.onnx",
                 ),
                 tokens = "$modelDir/tokens.txt",
-                modelType = "zipformer2",
+                modelType = "transducer",
             )
         }
     }