diff --git a/binding/csharp/IP2Region.Net/IP2Region.Net.csproj b/binding/csharp/IP2Region.Net/IP2Region.Net.csproj
index dc0e1ab..83901fe 100644
--- a/binding/csharp/IP2Region.Net/IP2Region.Net.csproj
+++ b/binding/csharp/IP2Region.Net/IP2Region.Net.csproj
@@ -2,7 +2,7 @@
 
     <PropertyGroup>
         <id>IP2Region.Net</id>
-        <version>3.0.0</version>
+        <version>2.1.1</version>
         <title>IP2Region.Net</title>
         <authors>Alan Lee</authors>
         <PackageLicenseExpression>Apache-2.0</PackageLicenseExpression>
diff --git a/binding/csharp/IP2Region.Net/Internal/Abstractions/AbstractCacheStrategy.cs b/binding/csharp/IP2Region.Net/Internal/Abstractions/AbstractCacheStrategy.cs
index d94524b..909f75c 100644
--- a/binding/csharp/IP2Region.Net/Internal/Abstractions/AbstractCacheStrategy.cs
+++ b/binding/csharp/IP2Region.Net/Internal/Abstractions/AbstractCacheStrategy.cs
@@ -15,10 +15,11 @@ internal abstract class AbstractCacheStrategy(string xdbPath)
     protected const int VectorIndexSize = 8;
 
     private const int BufferSize = 64 * 1024;
-    private readonly FileStream _xdbFileStream = new(xdbPath, FileMode.Open, FileAccess.Read, FileShare.Read, BufferSize, FileOptions.RandomAccess);
 
     public int IoCount { get; private set; }
 
+    protected FileStream XdbFileStream = new(xdbPath, FileMode.Open, FileAccess.Read, FileShare.Read, BufferSize, FileOptions.RandomAccess);
+
     public void ResetIoCount()
     {
         IoCount = 0;
@@ -26,24 +27,18 @@ internal abstract class AbstractCacheStrategy(string xdbPath)
 
     public virtual ReadOnlyMemory<byte> GetVectorIndex(int offset) => GetData(HeaderInfoLength + offset, VectorIndexSize);
 
-    public virtual ReadOnlyMemory<byte> GetData(int offset = 0, int length = 0)
+    public virtual ReadOnlyMemory<byte> GetData(long offset, int length)
     {
-        if (length == 0)
-        {
-            length = (int)_xdbFileStream.Length;
-        }
-
         byte[] buffer = ArrayPool<byte>.Shared.Rent(length);
         int totalBytesRead = 0;
         try
         {
-            _xdbFileStream.Seek(offset, SeekOrigin.Begin);
+            XdbFileStream.Seek(offset, SeekOrigin.Begin);
 
             int bytesRead;
             while (totalBytesRead < length)
             {
-                int bytesToRead = Math.Min(BufferSize, length - totalBytesRead);
-                bytesRead = _xdbFileStream.Read(buffer, totalBytesRead, bytesToRead);
+                bytesRead = XdbFileStream.Read(buffer, totalBytesRead, length);
                 totalBytesRead += bytesRead;
 
                 IoCount++;
diff --git a/binding/csharp/IP2Region.Net/Internal/ContentCacheStrategy.cs b/binding/csharp/IP2Region.Net/Internal/ContentCacheStrategy.cs
index cc88359..135751d 100644
--- a/binding/csharp/IP2Region.Net/Internal/ContentCacheStrategy.cs
+++ b/binding/csharp/IP2Region.Net/Internal/ContentCacheStrategy.cs
@@ -15,8 +15,10 @@ class ContentCacheStrategy : AbstractCacheStrategy
 
     public ContentCacheStrategy(string xdbPath) : base(xdbPath)
     {
-        _cacheData = base.GetData();
+        _cacheData = base.GetData(0, (int)XdbFileStream.Length);
+        XdbFileStream.Close();
+        XdbFileStream.Dispose();
     }
 
-    public override ReadOnlyMemory<byte> GetData(int offset = 0, int length = 0) => _cacheData.Slice(offset, length);
+    public override ReadOnlyMemory<byte> GetData(long offset = 0, int length = 0) => _cacheData.Slice((int)offset, length);
 }
diff --git a/binding/csharp/IP2Region.Net/Internal/VectorIndexCacheStrategy.cs b/binding/csharp/IP2Region.Net/Internal/VectorIndexCacheStrategy.cs
index 8ea0b01..b5abc17 100644
--- a/binding/csharp/IP2Region.Net/Internal/VectorIndexCacheStrategy.cs
+++ b/binding/csharp/IP2Region.Net/Internal/VectorIndexCacheStrategy.cs
@@ -18,7 +18,10 @@ class VectorIndexCacheStrategy : AbstractCacheStrategy
 
     public VectorIndexCacheStrategy(string xdbPath) : base(xdbPath)
     {
-        _vectorCache = GetData(HeaderInfoLength, VectorIndexRows * VectorIndexCols * VectorIndexSize);
+        XdbFileStream.Seek(HeaderInfoLength, SeekOrigin.Begin);
+        var buffer = new byte[VectorIndexRows * VectorIndexCols * VectorIndexSize];
+        var length = XdbFileStream.Read(buffer, 0, buffer.Length);
+        _vectorCache = new ReadOnlyMemory<byte>(buffer);
     }
 
     public override ReadOnlyMemory<byte> GetVectorIndex(int offset) => _vectorCache.Slice(offset, VectorIndexSize);