diff --git a/Octokit/Exceptions/RepositoryFormatException.cs b/Octokit/Exceptions/RepositoryFormatException.cs
new file mode 100644
index 00000000..941a1669
--- /dev/null
+++ b/Octokit/Exceptions/RepositoryFormatException.cs
@@ -0,0 +1,65 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Globalization;
+using System.Linq;
+using System.Runtime.Serialization;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Octokit
+{
+#if !NETFX_CORE
+    [Serializable]
+#endif
+    [SuppressMessage("Microsoft.Design", "CA1032:ImplementStandardExceptionConstructors",
+        Justification = "These exceptions are specific to the GitHub API and not general purpose exceptions")]
+    public class RepositoryFormatException : Exception
+    {
+        readonly string message;
+
+        public RepositoryFormatException(IEnumerable<string> invalidRepositories)
+        {
+            var parameterList = string.Join(", ", invalidRepositories);
+            message = string.Format(
+                CultureInfo.InvariantCulture,
+                "The list of repositories must be formatted as 'owner/name' - these values don't match this rule: {0}",
+                parameterList);
+
+        }
+
+        public override string Message
+        {
+            get
+            {
+                return message;
+            }
+        }
+
+        #if !NETFX_CORE
+        /// <summary>
+        /// Constructs an instance of LoginAttemptsExceededException
+        /// </summary>
+        /// <param name="info">
+        /// The <see cref="SerializationInfo"/> that holds the
+        /// serialized object data about the exception being thrown.
+        /// </param>
+        /// <param name="context">
+        /// The <see cref="StreamingContext"/> that contains
+        /// contextual information about the source or destination.
+        /// </param>
+        protected RepositoryFormatException(SerializationInfo info, StreamingContext context)
+            : base(info, context)
+        {
+            if (info == null) return;
+            message = info.GetString("Message");
+        }
+
+        public override void GetObjectData(SerializationInfo info, StreamingContext context)
+        {
+            base.GetObjectData(info, context);
+            info.AddValue("Message", Message);
+        }
+#endif
+    }
+}
diff --git a/Octokit/Octokit-Mono.csproj b/Octokit/Octokit-Mono.csproj
index 42a94494..db3f3233 100644
--- a/Octokit/Octokit-Mono.csproj
+++ b/Octokit/Octokit-Mono.csproj
@@ -396,6 +396,7 @@
     <Compile Include="Exceptions\TwoFactorAuthorizationException.cs" />
     <Compile Include="Http\HttpMessageHandlerFactory.cs" />
     <Compile Include="Models\Response\TeamMembership.cs" />
+    <Compile Include="Exceptions\RepositoryFormatException.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
 </Project>
\ No newline at end of file
diff --git a/Octokit/Octokit-MonoAndroid.csproj b/Octokit/Octokit-MonoAndroid.csproj
index 8077c4c4..7c7c420b 100644
--- a/Octokit/Octokit-MonoAndroid.csproj
+++ b/Octokit/Octokit-MonoAndroid.csproj
@@ -412,6 +412,7 @@
     <Compile Include="Models\Request\RepositoryHookTestRequest.cs" />
     <Compile Include="Http\HttpMessageHandlerFactory.cs" />
     <Compile Include="Models\Response\TeamMembership.cs" />
+    <Compile Include="Exceptions\RepositoryFormatException.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildExtensionsPath)\Novell\Novell.MonoDroid.CSharp.targets" />
 </Project>
\ No newline at end of file
diff --git a/Octokit/Octokit-Monotouch.csproj b/Octokit/Octokit-Monotouch.csproj
index 61fb07ff..810d8272 100644
--- a/Octokit/Octokit-Monotouch.csproj
+++ b/Octokit/Octokit-Monotouch.csproj
@@ -405,6 +405,7 @@
     <Compile Include="Models\Request\RepositoryHookTestRequest.cs" />
     <Compile Include="Http\HttpMessageHandlerFactory.cs" />
     <Compile Include="Models\Response\TeamMembership.cs" />
+    <Compile Include="Exceptions\RepositoryFormatException.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildExtensionsPath)\Xamarin\iOS\Xamarin.MonoTouch.CSharp.targets" />
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
diff --git a/Octokit/Octokit-Portable.csproj b/Octokit/Octokit-Portable.csproj
index 59b0edd0..855578f9 100644
--- a/Octokit/Octokit-Portable.csproj
+++ b/Octokit/Octokit-Portable.csproj
@@ -394,6 +394,7 @@
     <Compile Include="Exceptions\TwoFactorAuthorizationException.cs" />
     <Compile Include="Http\HttpMessageHandlerFactory.cs" />
     <Compile Include="Models\Response\TeamMembership.cs" />
+    <Compile Include="Exceptions\RepositoryFormatException.cs" />
   </ItemGroup>
   <ItemGroup>
     <CodeAnalysisDictionary Include="..\CustomDictionary.xml">
diff --git a/Octokit/Octokit-netcore45.csproj b/Octokit/Octokit-netcore45.csproj
index 2b011805..4857f2c6 100644
--- a/Octokit/Octokit-netcore45.csproj
+++ b/Octokit/Octokit-netcore45.csproj
@@ -398,6 +398,7 @@
     <Compile Include="Exceptions\TwoFactorAuthorizationException.cs" />
     <Compile Include="Http\HttpMessageHandlerFactory.cs" />
     <Compile Include="Models\Response\TeamMembership.cs" />
+    <Compile Include="Exceptions\RepositoryFormatException.cs" />
   </ItemGroup>
   <ItemGroup>
     <CodeAnalysisDictionary Include="..\CustomDictionary.xml">
diff --git a/Octokit/Octokit.csproj b/Octokit/Octokit.csproj
index 6b0fed00..a003617f 100644
--- a/Octokit/Octokit.csproj
+++ b/Octokit/Octokit.csproj
@@ -74,6 +74,7 @@
     <Compile Include="Clients\RepositoryContentsClient.cs" />
     <Compile Include="Exceptions\PrivateRepositoryQuotaExceededException.cs" />
     <Compile Include="Exceptions\RepositoryExistsException.cs" />
+    <Compile Include="Exceptions\RepositoryFormatException.cs" />
     <Compile Include="Exceptions\TwoFactorAuthorizationException.cs" />
     <Compile Include="Helpers\ApiErrorExtensions.cs" />
     <Compile Include="Helpers\ApiUrls.Authorizations.cs" />