diff --git a/csharp/src/Google.Protobuf/InvalidProtocolBufferException.cs b/csharp/src/Google.Protobuf/InvalidProtocolBufferException.cs
new file mode 100644
index 0000000..eeb0f13
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+++ b/csharp/src/Google.Protobuf/InvalidProtocolBufferException.cs
@@ -0,0 +1,129 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.IO;
+
+namespace Google.Protobuf
+{
+    /// <summary>
+    /// Thrown when a protocol message being parsed is invalid in some way,
+    /// e.g. it contains a malformed varint or a negative byte length.
+    /// </summary>
+    public sealed class InvalidProtocolBufferException : IOException
+    {
+        internal InvalidProtocolBufferException(string message)
+            : base(message)
+        {
+        }
+
+        internal InvalidProtocolBufferException(string message, Exception innerException)
+            : base(message, innerException)
+        {
+        }
+
+        internal static InvalidProtocolBufferException MoreDataAvailable()
+        {
+            return new InvalidProtocolBufferException(
+                "Completed reading a message while more data was available in the stream.");
+        }
+
+        internal static InvalidProtocolBufferException TruncatedMessage()
+        {
+            return new InvalidProtocolBufferException(
+                "While parsing a protocol message, the input ended unexpectedly " +
+                "in the middle of a field.  This could mean either than the " +
+                "input has been truncated or that an embedded message " +
+                "misreported its own length.");
+        }
+
+        internal static InvalidProtocolBufferException NegativeSize()
+        {
+            return new InvalidProtocolBufferException(
+                "CodedInputStream encountered an embedded string or message " +
+                "which claimed to have negative size.");
+        }
+
+        internal static InvalidProtocolBufferException MalformedVarint()
+        {
+            return new InvalidProtocolBufferException(
+                "CodedInputStream encountered a malformed varint.");
+        }
+
+        /// <summary>
+        /// Creates an exception for an error condition of an invalid tag being encountered.
+        /// </summary>
+        internal static InvalidProtocolBufferException InvalidTag()
+        {
+            return new InvalidProtocolBufferException(
+                "Protocol message contained an invalid tag (zero).");
+        }
+
+        internal static InvalidProtocolBufferException InvalidBase64(Exception innerException)
+        {
+            return new InvalidProtocolBufferException("Invalid base64 data", innerException);
+        }
+
+        internal static InvalidProtocolBufferException InvalidEndTag()
+        {
+            return new InvalidProtocolBufferException(
+                "Protocol message end-group tag did not match expected tag.");
+        }
+
+        internal static InvalidProtocolBufferException RecursionLimitExceeded()
+        {
+            return new InvalidProtocolBufferException(
+                "Protocol message had too many levels of nesting.  May be malicious.  " +
+                "Use CodedInputStream.SetRecursionLimit() to increase the depth limit.");
+        }
+
+        internal static InvalidProtocolBufferException JsonRecursionLimitExceeded()
+        {
+            return new InvalidProtocolBufferException(
+                "Protocol message had too many levels of nesting.  May be malicious.  " +
+                "Use JsonParser.Settings to increase the depth limit.");
+        }
+
+        internal static InvalidProtocolBufferException SizeLimitExceeded()
+        {
+            return new InvalidProtocolBufferException(
+                "Protocol message was too large.  May be malicious.  " +
+                "Use CodedInputStream.SetSizeLimit() to increase the size limit.");
+        }
+
+        internal static InvalidProtocolBufferException InvalidMessageStreamTag()
+        {
+            return new InvalidProtocolBufferException(
+                "Stream of protocol messages had invalid tag. Expected tag is length-delimited field 1.");
+        }
+    }
+}
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