NullPointerException at ... RequestUtils.forwardURL
错误信息 java.lang.NullPointerException at org.apache.struts.util.RequestUtils.forwardURL (RequestUtils.java:1223)
可能原因
lMissing path attribute in the forward subelement of the action element in struts-config.xml
相关链接
Cannot find bean org.apache.struts.taglib.html.BEAN in any scope
错误信息 javax.servlet.jsp.JspException: Cannot find bean org.apache.struts.taglib.html.BEAN in any scope
可能原因
lTrying to use Struts form subelement tags outside of the Struts form tag.
相关链接
lUsing form subelements outside of a form tag http://forum.java.sun.com/thread.jsp?thread=337537&forum=4&message=1384153
Missing message for key xx.xx.xx
错误信息 javax.servlet.jsp.JspException: Missing message for key xx.xx.xx
可能原因
lThe key-value pair with specified key is not in ApplicationResources.properties file
lApplicationResources.properties file not in classpath (not in WEB-INF/classes directory in specified location)
相关链接
Cannot find message resources under key org.apache.struts.action.MESSAGE
错误信息 Cannot find message resources under key org.apache.struts.action.MESSAGE
可能原因
lExplicitly trying to use message resources that are not available (such as ApplicationResources.properties not available
lImplicitly trying to use message resources that are not available (such as using empty html:options tag instead of specifying the options in its body -- this assumes options are specified in ApplicationResources.properties file)
lXML parser issues -- too many, too few, incorrect/incompatible versions
相关链接
lXML Parser Issues http://www.mail-archive.com/struts-user@jakarta.apache.org/msg15779.html

No input attribute for mapping path /loginAction
错误信息 No input attribute for mapping path /xxxxAction
可能原因
lNo input attribute in action mapping in struts-config.xml file for the action with the name specified in the error message. An input attribute is not required if form validation is not performed (either because the validate attribute is set to false or because the validation method in the relevant form class is not implemented. The input attribute specifies the page leading to this action because that page is used to display error messages from the form validation.
相关链接
Strange Output Characters （页面乱码）
错误信息 Strange and seemingly random characters in HTML and on screen, but not in original JSP or servlet.
可能原因
lRegular HTML form tags intermixed incorrectly with Struts html:form tags.
HTML标签与Struts标签不正确的混合使用
lEncoding style used does not support characters used in page.
使用了JSP页面不支持的编码
相关链接
"Document contained no data" or no data rendered on page （空白页面）
错误信息
l"Document contained no data" in Netscape （在Netscape中显示“文件中无数据”）
lNo data rendered (completely empty) page in Microsoft Internet Explorer（在IE中为空白页面，无任何显示信息）
可能原因
lEmploying a descendent of the Action class that does not implement the perform() method while using the Struts 1.0 libraries. Struts 1.1 Action child classes started using execute() rather than perform(), but is backwards compatible and supports the perform() method. However, if you write an Action-descended class for Struts 1.1 with an execute() method and try to run it in Struts 1.0, you will get this "Document contained no data" error message in Netscape or a completely empty (no HTML whatsoever) page rendered in Microsoft Internet Explorer.
l用Struts1.1写的应用在struts1.0环境中运行时，可能出现此问题。
相关链接


其它错误信息
编译JSP文件时出现错误：
java.lang.NullPointerException
error:org.apache.jasper.JasperException: Error compiling \JSPs\security\appUserCreate.jsp
可能原因：
JSP页面中的Struts标记有语法错误。
例如：<bean:message key=”button.submit”> 错误原因：右边的括号前缺少斜杠“/”
正确的为：<bean:message key=”button.submit”/>

不同语言资源文件中的Key不匹配。