/*
 * Copyright 2002-2013 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.springframework.security.web.csrf;

/**
 * Thrown when no expected {@link CsrfToken} is found but is required.
 *
 * @author Rob Winch
 * @since 3.2
 */
@SuppressWarnings("serial")
public class MissingCsrfTokenException extends CsrfException {

	public MissingCsrfTokenException(String actualToken) {
		super("Expected CSRF token not found. Has your session expired?");
	}
}
@@ -940,64 +940,84 @@
 er(%22
-Expected CSRF token not found. Has your session expired?
+Could not verify the provided CSRF token because your session was not found.
 %22);%0A

Improve CSRF missing error message