diff --git a/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/participants/XMLSchemaErrorCode.java b/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/participants/XMLSchemaErrorCode.java
index ebc900d46c..100ad37f98 100644
--- a/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/participants/XMLSchemaErrorCode.java
+++ b/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/participants/XMLSchemaErrorCode.java
@@ -24,6 +24,7 @@
 import org.eclipse.lemminx.dom.DOMNode;
 import org.eclipse.lemminx.dom.NoNamespaceSchemaLocation;
 import org.eclipse.lemminx.dom.SchemaLocation;
+import org.eclipse.lemminx.extensions.contentmodel.participants.codeactions.TargetNamespace_1CodeAction;
 import org.eclipse.lemminx.extensions.contentmodel.participants.codeactions.cvc_attribute_3CodeAction;
 import org.eclipse.lemminx.extensions.contentmodel.participants.codeactions.cvc_complex_type_2_1CodeAction;
 import org.eclipse.lemminx.extensions.contentmodel.participants.codeactions.cvc_complex_type_2_3CodeAction;
@@ -74,6 +75,7 @@ public enum XMLSchemaErrorCode implements IXMLErrorCode {
 	cvc_maxInclusive_valid("cvc-maxInclusive-valid"), // https://wiki.xmldation.com/Support/validator/cvc-maxinclusive-valid
 	cvc_minExclusive_valid("cvc-minExclusive-valid"), // https://wiki.xmldation.com/Support/validator/cvc-minexclusive-valid
 	cvc_minInclusive_valid("cvc-minInclusive-valid"), // https://wiki.xmldation.com/Support/validator/cvc-mininclusive-valid
+	TargetNamespace_1("TargetNamespace.1"), //
 	TargetNamespace_2("TargetNamespace.2"), SchemaLocation("SchemaLocation"), schema_reference_4("schema_reference.4"), //
 	src_element_3("src-element.3");
 
@@ -138,7 +140,6 @@ public static Range toLSPRange(XMLLocator location, XMLSchemaErrorCode code, Obj
 		case cvc_elt_1_a:
 		case cvc_complex_type_4:
 		case src_element_3:
-		case TargetNamespace_2:
 			return XMLPositionUtility.selectStartTagName(offset, document);
 		case cvc_complex_type_3_2_2: {
 			String attrName = getString(arguments[1]);
@@ -245,6 +246,10 @@ public static Range toLSPRange(XMLLocator location, XMLSchemaErrorCode code, Obj
 		}
 		case cvc_type_3_1_2:
 			return XMLPositionUtility.selectStartTagName(offset, document);
+		case TargetNamespace_1:
+			return XMLPositionUtility.selectRootAttributeValue("xmlns", document);
+		case TargetNamespace_2:
+			return XMLPositionUtility.selectRootStartTag(document);
 		default:
 		}
 		return null;
@@ -260,5 +265,6 @@ public static void registerCodeActionParticipants(Map<String, ICodeActionPartici
 		codeActions.put(cvc_complex_type_3_2_2.getCode(), new cvc_complex_type_3_2_2CodeAction());
 		codeActions.put(cvc_enumeration_valid.getCode(), new cvc_enumeration_validCodeAction());
 		codeActions.put(cvc_complex_type_2_1.getCode(), new cvc_complex_type_2_1CodeAction());
+		codeActions.put(TargetNamespace_1.getCode(), new TargetNamespace_1CodeAction());
 	}
 }
diff --git a/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/participants/XMLSyntaxErrorCode.java b/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/participants/XMLSyntaxErrorCode.java
index 49cde45219..98d5bf4be0 100644
--- a/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/participants/XMLSyntaxErrorCode.java
+++ b/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/participants/XMLSyntaxErrorCode.java
@@ -22,6 +22,7 @@
 import org.apache.xerces.xni.XMLLocator;
 import org.eclipse.lemminx.dom.DOMDocument;
 import org.eclipse.lemminx.dom.DOMDocumentType;
+import org.eclipse.lemminx.dom.DOMNode;
 import org.eclipse.lemminx.extensions.contentmodel.participants.codeactions.ETagRequiredCodeAction;
 import org.eclipse.lemminx.extensions.contentmodel.participants.codeactions.ElementUnterminatedCodeAction;
 import org.eclipse.lemminx.extensions.contentmodel.participants.codeactions.EqRequiredInAttributeCodeAction;
diff --git a/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/participants/codeactions/TargetNamespace_1CodeAction.java b/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/participants/codeactions/TargetNamespace_1CodeAction.java
new file mode 100644
index 0000000000..6340393e9d
--- /dev/null
+++ b/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/participants/codeactions/TargetNamespace_1CodeAction.java
@@ -0,0 +1,55 @@
+/**
+ * Copyright (c) 2020 Red Hat Inc. and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v2.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v20.html
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ * Red Hat Inc. - initial API and implementation
+ */
+package org.eclipse.lemminx.extensions.contentmodel.participants.codeactions;
+
+import java.util.List;
+import java.util.regex.Pattern;
+import java.util.regex.Matcher;
+
+import org.eclipse.lemminx.commons.CodeActionFactory;
+import org.eclipse.lemminx.dom.DOMDocument;
+import org.eclipse.lemminx.services.extensions.ICodeActionParticipant;
+import org.eclipse.lemminx.services.extensions.IComponentProvider;
+import org.eclipse.lemminx.settings.EnforceQuoteStyle;
+import org.eclipse.lemminx.settings.SharedSettings;
+import org.eclipse.lsp4j.CodeAction;
+import org.eclipse.lsp4j.Diagnostic;
+import org.eclipse.lsp4j.Range;
+
+public class TargetNamespace_1CodeAction implements ICodeActionParticipant {
+
+	private static final Pattern NAMESPACE_EXTRACTOR = Pattern.compile("'([^']+)'\\.");
+
+	@Override
+	public void doCodeAction(Diagnostic diagnostic, Range range, DOMDocument document, List<CodeAction> codeActions,
+			SharedSettings sharedSettings, IComponentProvider componentProvider) {
+		
+		Matcher namespaceMatcher = NAMESPACE_EXTRACTOR.matcher(diagnostic.getMessage());
+		if (namespaceMatcher.find()){
+			String correctNamespace = namespaceMatcher.group(1);
+			String quote = "\"";
+			if (sharedSettings.getFormattingSettings().getEnforceQuoteStyle() == EnforceQuoteStyle.preferred) {
+				quote = sharedSettings.getPreferences().getQuotationAsString();
+			}
+			// @formatter:off
+			CodeAction replaceNamespace = CodeActionFactory.replace(
+					"Replace with '" + correctNamespace + "'",
+					diagnostic.getRange(),
+					quote + correctNamespace + quote,
+					document.getTextDocument(), diagnostic);
+			// @formatter:on
+			codeActions.add(replaceNamespace);
+		}
+	}
+
+}
diff --git a/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/utils/XMLPositionUtility.java b/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/utils/XMLPositionUtility.java
index 5f1749faf7..e5c354b267 100644
--- a/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/utils/XMLPositionUtility.java
+++ b/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/utils/XMLPositionUtility.java
@@ -325,6 +325,21 @@ public static Range selectRootStartTag(DOMDocument document) {
 		return selectStartTagName(root);
 	}
 
+	public static Range selectRootAttributeValue(String attrName, DOMDocument document) {
+		DOMNode root = document.getDocumentElement();
+		if (root == null) {
+			root = document.getChild(0);
+		}
+		if (root == null) {
+			return null;
+		}
+		DOMAttr attr = root.getAttributeNode(attrName);
+		if (attr == null) {
+			return null;
+		}
+		return selectAttributeValue(attr);
+	}
+
 	public static Range selectStartTagName(int offset, DOMDocument document) {
 		DOMNode element = document.findNodeAt(offset);
 		if (element != null) {
diff --git a/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/extensions/contentmodel/XMLSchemaDiagnosticsTest.java b/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/extensions/contentmodel/XMLSchemaDiagnosticsTest.java
index e6d811ad1b..282f3b766f 100644
--- a/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/extensions/contentmodel/XMLSchemaDiagnosticsTest.java
+++ b/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/extensions/contentmodel/XMLSchemaDiagnosticsTest.java
@@ -577,6 +577,28 @@ public void cvc_complex_type_2_2_withText() throws Exception {
 		testDiagnosticsFor(xml, diagnosticBob, diagnostic_cvc_2_2);
 	}
 
+	@Test
+	public void testTargetNamespace_1Normal() throws Exception {
+		String xml = "<?xml version=\"1.0\" encoding=\"UTF-8\" ?>\n" + //
+				"<?xml-model href=\"src/test/resources/xsd/two-letter-name.xsd\"?>\n" + //
+				"<two-letter-name xmlns=\"BAD_NS\">Io</two-letter-name>";
+		testDiagnosticsFor(xml,
+				d(2, 23, 2, 31, XMLSchemaErrorCode.TargetNamespace_1, "TargetNamespace.1: Expecting namespace 'BAD_NS', but the target namespace of the schema document is 'http://two-letter-name'."),
+				d(2, 1, 2, 16, XMLSchemaErrorCode.cvc_elt_1_a, "cvc-elt.1.a: Cannot find the declaration of element 'two-letter-name'.")
+		);
+	}
+
+	@Test
+	public void testTargetNamespace_1ShortNS() throws Exception {
+		String xml = "<?xml version=\"1.0\" encoding=\"UTF-8\" ?>\n" + //
+				"<?xml-model href=\"src/test/resources/xsd/two-letter-name.xsd\"?>\n" + //
+				"<two-letter-name xmlns=\"_\">Io</two-letter-name>";
+		testDiagnosticsFor(xml,
+				d(2, 23, 2, 26, XMLSchemaErrorCode.TargetNamespace_1, "TargetNamespace.1: Expecting namespace '_', but the target namespace of the schema document is 'http://two-letter-name'."),
+				d(2, 1, 2, 16, XMLSchemaErrorCode.cvc_elt_1_a, "cvc-elt.1.a: Cannot find the declaration of element 'two-letter-name'.")
+		);
+	}
+
 	private static void testDiagnosticsFor(String xml, Diagnostic... expected) {
 		XMLAssert.testDiagnosticsFor(xml, "src/test/resources/catalogs/catalog.xml", expected);
 	}
diff --git a/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/extensions/contentmodel/XMLSyntaxDiagnosticsTest.java b/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/extensions/contentmodel/XMLSyntaxDiagnosticsTest.java
index f2932f912f..0db6fc2dda 100644
--- a/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/extensions/contentmodel/XMLSyntaxDiagnosticsTest.java
+++ b/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/extensions/contentmodel/XMLSyntaxDiagnosticsTest.java
@@ -19,6 +19,7 @@
 import static org.eclipse.lemminx.XMLAssert.testDiagnosticsFor;
 
 import org.eclipse.lemminx.XMLAssert;
+import org.eclipse.lemminx.extensions.contentmodel.participants.XMLSchemaErrorCode;
 import org.eclipse.lemminx.extensions.contentmodel.participants.XMLSyntaxErrorCode;
 import org.eclipse.lemminx.settings.EnforceQuoteStyle;
 import org.eclipse.lemminx.settings.QuoteStyle;
diff --git a/org.eclipse.lemminx/src/test/resources/xsd/two-letter-name.xsd b/org.eclipse.lemminx/src/test/resources/xsd/two-letter-name.xsd
new file mode 100644
index 0000000000..83ede5f3a1
--- /dev/null
+++ b/org.eclipse.lemminx/src/test/resources/xsd/two-letter-name.xsd
@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="http://two-letter-name">
+    <xs:element name="two-letter-name">
+        <xs:simpleType>
+            <xs:restriction base="xs:token">
+                <xs:pattern value="[A-Z][a-z]"></xs:pattern>
+            </xs:restriction>
+        </xs:simpleType>
+    </xs:element>
+</xs:schema>
\ No newline at end of file