Google Web Toolkit: upgrade gwt 2.7 to gwt 2.8.1 not working

Hi everyone

I develop application in gwt and google app engine.

until now i used with gwt 2.7 lib and google app engine 1.51 lib

i try to upgrade the gwt 2.7 to 2.8.1 lib

and i have 2 problems now

i hope you can help me

1) when i try to run the project i get exception in devModeBase.class file in run method

this is the log of run + exception:

Running CodeServer with parameters: [-noprecompile, -port, 65462, -sourceLevel, 1.8, -bindAddress, 127.0.0.1, -launcherDir, /Users/gallavie/Documents/workspace/Darimpo/war, -logLevel, INFO, -style, OBFUSCATED, com.darimpo.Darimpo, com.darimpo.Darimpo]

Super Dev Mode starting up

workDir: /var/folders/fj/8gtg078929j8hjtfzyy5srv40000gn/T/gwt-codeserver-8030568012575356208.tmp

2017-05-10 06:44:10.582:INFO::main: Logging initialized @3822ms

Loading Java files in com.darimpo.Darimpo.

Ignored 33 units with compilation errors in first pass.

Compile with -strict or with -logLevel set to TRACE or DEBUG to see all errors.

Module setup completed in 4961 ms

Loading Java files in com.darimpo.Darimpo.

Ignored 33 units with compilation errors in first pass.

Compile with -strict or with -logLevel set to TRACE or DEBUG to see all errors.

Module setup completed in 1273 ms

2017-05-10 06:44:15.046:INFO:oejs.Server:main: jetty-9.2.z-SNAPSHOT

2017-05-10 06:44:15.164:INFO:oejsh.ContextHandler:main: Started o.e.j.s.ServletContextHandler@7a508fdc{/,null,AVAILABLE}

2017-05-10 06:44:15.301:INFO:oejs.ServerConnector:main: Started ServerConnector@4ca4b342{HTTP/1.1}{127.0.0.1:65462}

2017-05-10 06:44:15.313:INFO:oejs.Server:main: Started @8553ms

The code server is ready at http://127.0.0.1:65462/

Code server started in 6.828 s ms

2017-05-10 06:44:15.702:INFO:oejs.Server:main: jetty-9.2.z-SNAPSHOT

2017-05-10 06:44:19.948:WARN:oejuc.AbstractLifeCycle:main: FAILED org.eclipse.jetty.annotations.ServletContainerInitializersStarter@1e23623: java.lang.NoSuchMethodError: javax.servlet.ServletContext.getJspConfigDescriptor()Ljavax/servlet/descriptor/JspConfigDescriptor;

java.lang.NoSuchMethodError: javax.servlet.ServletContext.getJspConfigDescriptor()Ljavax/servlet/descriptor/JspConfigDescriptor;

at org.apache.jasper.servlet.TldScanner.scanJspConfig(TldScanner.java:148)

at org.apache.jasper.servlet.TldScanner.scan(TldScanner.java:97)

at org.apache.jasper.servlet.JasperInitializer.onStartup(JasperInitializer.java:103)

at org.eclipse.jetty.plus.annotation.ContainerInitializer.callStartup(ContainerInitializer.java:140)

at org.eclipse.jetty.annotations.ServletContainerInitializersStarter.doStart(ServletContainerInitializersStarter.java:65)

at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)

at org.eclipse.jetty.servlet.ServletContextHandler.startContext(ServletContextHandler.java:274)

at org.eclipse.jetty.webapp.WebAppContext.startWebapp(WebAppContext.java:1349)

at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1342)

at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:741)

at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:505)

at com.google.gwt.dev.shell.jetty.JettyLauncher$WebAppContextWithReload.doStart(JettyLauncher.java:550)

at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)

at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132)

at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:114)

at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:61)

at org.eclipse.jetty.server.handler.RequestLogHandler.doStart(RequestLogHandler.java:140)

at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)

at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132)

at org.eclipse.jetty.server.Server.start(Server.java:387)

at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:114)

at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:61)

at org.eclipse.jetty.server.Server.doStart(Server.java:354)

at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)

at com.google.gwt.dev.shell.jetty.JettyLauncher.start(JettyLauncher.java:760)

at com.google.gwt.dev.DevMode.doStartUpServer(DevMode.java:636)

at com.google.gwt.dev.DevModeBase.startUp(DevModeBase.java:923)

at com.google.gwt.dev.DevModeBase.run(DevModeBase.java:706)

at com.google.gwt.dev.DevMode.main(DevMode.java:432)

2017-05-10 06:44:19.952:WARN:oejuc.AbstractLifeCycle:main: FAILED c.g.g.d.s.j.WebAppContextWithReload@eb55e46{/,file:/Users/gallavie/Documents/workspace/Darimpo/war/,STARTING}{/Users/gallavie/Documents/workspace/Darimpo/war}: java.lang.NoSuchMethodError: javax.servlet.ServletContext.getJspConfigDescriptor()Ljavax/servlet/descriptor/JspConfigDescriptor;