Dear Experts,

I have been using Apache for quite some time now. Some times I get peculiar types of problems that I am often not able to resolve.

I was doing some lab preparation with Tomcat 5.0.24. it was working fine. but all on a sudden I started getting this error. I tried with another version Tomcat 5.0.28 and also 5.0.12 but all versions keep on giving the same error. I restarted my computer but I still get this error.

I am a demonstartor of a lab and often I face this problem with my Tomcat
servers. are this problems due to some mistake of mine? is there anything that I can do to correct this problem when it happens.
please know that most of the times Tomcats run fine, but about 25% time I get this problem. the error I get is the one below or something similar:
please Help me.



SEVERE: An exception or error occurred in the container during the request proce
ssing
java.lang.NoSuchMethodError: javax.servlet.http.HttpServletRequest.removeAttrib u
te(Ljava/lang/String V
at org.apache.catalina.core.StandardWrapperValve.invo ke(StandardWrapperV
alve.java:278)
at org.apache.catalina.core.StandardValveContext.invo keNext(StandardValv
eContext.java:104)
at org.apache.catalina.core.StandardPipeline.invoke(S tandardPipeline.jav
a:520)
at org.apache.catalina.core.StandardContextValve.invo keInternal(Standard
ContextValve.java:198)
at org.apache.catalina.core.StandardContextValve.invo ke(StandardContextV
alve.java:152)
at org.apache.catalina.core.StandardValveContext.invo keNext(StandardValv
eContext.java:104)
at org.apache.catalina.core.StandardPipeline.invoke(S tandardPipeline.jav
a:520)
at org.apache.catalina.core.StandardHostValve.invoke( StandardHostValve.j
ava:137)
at org.apache.catalina.core.StandardValveContext.invo keNext(StandardValv
eContext.java:104)
at org.apache.catalina.valves.ErrorReportValve.invoke (ErrorReportValve.j
ava:118)
at org.apache.catalina.core.StandardValveContext.invo keNext(StandardValv
eContext.java:102)
at org.apache.catalina.core.StandardPipeline.invoke(S tandardPipeline.jav
a:520)
at org.apache.catalina.core.StandardEngineValve.invok e(StandardEngineVal
ve.java:109)
at org.apache.catalina.core.StandardValveContext.invo keNext(StandardValv
eContext.java:104)
at org.apache.catalina.core.StandardPipeline.invoke(S tandardPipeline.jav
a:520)
at org.apache.catalina.core.ContainerBase.invoke(Cont ainerBase.java:929)

at org.apache.coyote.tomcat5.CoyoteAdapter.service(Co yoteAdapter.java:16
0)
at org.apache.coyote.http11.Http11Processor.process(H ttp11Processor.java
:799)
at org.apache.coyote.http11.Http11Protocol$Http11Conn ectionHandler.proce
ssConnection(Http11Protocol.java:705)
at org.apache.tomcat.util.net.TcpWorkerThread.runIt(P oolTcpEndpoint.java
:577)
at org.apache.tomcat.util.threads.ThreadPool$ControlR unnable.run(ThreadP
ool.java:683)
at java.lang.Thread.run(Thread.java:534)