Index: Ringtoets/Common/src/Ringtoets.Common.IO/Readers/ConfigurationReader.cs
===================================================================
diff -u -r8a00046f9112833f25944b0f2631c7003f7a1692 -r94587578a17566618ad7b26fc914d8b4d30fb99b
--- Ringtoets/Common/src/Ringtoets.Common.IO/Readers/ConfigurationReader.cs	(.../ConfigurationReader.cs)	(revision 8a00046f9112833f25944b0f2631c7003f7a1692)
+++ Ringtoets/Common/src/Ringtoets.Common.IO/Readers/ConfigurationReader.cs	(.../ConfigurationReader.cs)	(revision 94587578a17566618ad7b26fc914d8b4d30fb99b)
@@ -148,9 +148,10 @@
         /// <exception cref="CriticalFileReadException">Thrown when the provided XML document does not match the provided XML Schema Definition (XSD).</exception>
         private static void ValidateToSchema(XDocument document, string schemaString, string xmlFilePath)
         {
+            var xmlResourcesResolver = new XmlResourcesResolver();
             var xmlSchemaSet = new XmlSchemaSet
             {
-                XmlResolver = new XmlResourcesResolver()
+                XmlResolver = xmlResourcesResolver
             };
 
             try
@@ -163,6 +164,11 @@
                 throw new ArgumentException($"Invalid 'schemaString': {exception.Message}", exception);
             }
 
+            if (!xmlResourcesResolver.BaseSchemeReferenced)
+            {
+                throw new ArgumentException("Invalid 'schemaString': the base XML Schema Definition file 'ConfiguratieSchema.xsd' is not referenced.");
+            }
+
             try
             {
                 document.Validate(xmlSchemaSet, null);
@@ -229,11 +235,14 @@
                 }
             }
 
+            public bool BaseSchemeReferenced { get; private set; }
+
             public override object GetEntity(Uri absoluteUri, string role, Type ofObjectToReturn)
             {
                 switch (Path.GetFileName(absoluteUri.ToString()))
                 {
                     case "ConfiguratieSchema.xsd":
+                        BaseSchemeReferenced = true;
                         return new MemoryStream(Encoding.UTF8.GetBytes(Resources.ConfiguratieSchema));
                     case "StochastSchema.xsd":
                         return new MemoryStream(Encoding.UTF8.GetBytes(Resources.StochastSchema));
Index: Ringtoets/Common/test/Ringtoets.Common.IO.Test/Readers/ConfigurationReaderTest.cs
===================================================================
diff -u -r789a1cf222034a729160372a650c4b5249d1e796 -r94587578a17566618ad7b26fc914d8b4d30fb99b
--- Ringtoets/Common/test/Ringtoets.Common.IO.Test/Readers/ConfigurationReaderTest.cs	(.../ConfigurationReaderTest.cs)	(revision 789a1cf222034a729160372a650c4b5249d1e796)
+++ Ringtoets/Common/test/Ringtoets.Common.IO.Test/Readers/ConfigurationReaderTest.cs	(.../ConfigurationReaderTest.cs)	(revision 94587578a17566618ad7b26fc914d8b4d30fb99b)
@@ -124,7 +124,9 @@
         [TestCase("invalidXsdContent.xsd",
             "Invalid 'schemaString': The root element of a W3C XML Schema should be <schema> and its namespace should be 'http://www.w3.org/2001/XMLSchema'.",
             typeof(XmlSchemaException))]
-        public void Constructor_InvalidSchemaString_ThrowArgumentException(string fileName, string expectedMessage, Type expectedExceptionType)
+        [TestCase("notReferencingBaseXsd.xsd",
+            "Invalid 'schemaString': the base XML Schema Definition file 'ConfiguratieSchema.xsd' is not referenced.")]
+        public void Constructor_InvalidSchemaString_ThrowArgumentException(string fileName, string expectedMessage, Type expectedInnerExceptionType = null)
         {
             // Setup
             string filePath = Path.Combine(testDirectoryPath, "validConfiguration.xml");
@@ -136,7 +138,11 @@
             // Assert
             var exception = Assert.Throws<ArgumentException>(call);
             Assert.AreEqual(expectedMessage, exception.Message);
-            Assert.IsInstanceOf(expectedExceptionType, exception.InnerException);
+
+            if (expectedInnerExceptionType != null)
+            {
+                Assert.IsInstanceOf(expectedInnerExceptionType, exception.InnerException);
+            }
         }
 
         [Test]
@@ -198,7 +204,7 @@
 
         public ConfigurationReaderTest()
         {
-            schemaString = File.ReadAllText(Path.Combine(testDirectoryPath, "ConfiguratieSchema.xsd"));
+            schemaString = File.ReadAllText(Path.Combine(testDirectoryPath, "validConfigurationSchema.xsd"));
         }
 
         private class TestConfigurationReader : ConfigurationReader<TestReadConfigurationItem>
Fisheye: Tag 94587578a17566618ad7b26fc914d8b4d30fb99b refers to a dead (removed) revision in file `Ringtoets/Common/test/Ringtoets.Common.IO.Test/test-data/ConfigurationReader/ConfiguratieSchema.xsd'.
Fisheye: No comparison available.  Pass `N' to diff?
Index: Ringtoets/Common/test/Ringtoets.Common.IO.Test/test-data/ConfigurationReader/notReferencingBaseXsd.xsd
===================================================================
diff -u
--- Ringtoets/Common/test/Ringtoets.Common.IO.Test/test-data/ConfigurationReader/notReferencingBaseXsd.xsd	(revision 0)
+++ Ringtoets/Common/test/Ringtoets.Common.IO.Test/test-data/ConfigurationReader/notReferencingBaseXsd.xsd	(revision 94587578a17566618ad7b26fc914d8b4d30fb99b)
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
+  <xs:element name="test"/>
+</xs:schema>
\ No newline at end of file
Index: Ringtoets/Common/test/Ringtoets.Common.IO.Test/test-data/ConfigurationReader/validConfigurationSchema.xsd
===================================================================
diff -u
--- Ringtoets/Common/test/Ringtoets.Common.IO.Test/test-data/ConfigurationReader/validConfigurationSchema.xsd	(revision 0)
+++ Ringtoets/Common/test/Ringtoets.Common.IO.Test/test-data/ConfigurationReader/validConfigurationSchema.xsd	(revision 94587578a17566618ad7b26fc914d8b4d30fb99b)
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
+  <xs:redefine schemaLocation="ConfiguratieSchema.xsd">
+    <xs:complexType name="berekeningType">
+      <xs:complexContent>
+        <xs:extension base="berekeningType">
+          <xs:sequence>
+            <xs:element ref="test" minOccurs="0"/>
+          </xs:sequence>
+        </xs:extension>
+      </xs:complexContent>
+    </xs:complexType>
+  </xs:redefine>
+  <xs:element name="test">
+    <xs:simpleType>
+      <xs:restriction base="xs:double"/>
+    </xs:simpleType>
+  </xs:element>
+</xs:schema>
\ No newline at end of file