I created a custom MatrixExecutionStrategy (QAMatrixExecutionStrategyImpl) and when it is selected and the given job is already saved with QAMatrixExecutionStrategyImpl, error occurs when I modify job configuration and try to save the job.

Exception: java.lang.IllegalArgumentException: Failed to instantiate class hudson.matrix.MatrixExecutionStrategy from

{"stapler-class":["hudson.matrix.DefaultMatrixExecutionStrategyImpl","hudson.plugins.qamatrix.QAMatrixExecutionStrategyImpl"]}

Stacktrace:

javax.servlet.ServletException: java.lang.IllegalArgumentException: Failed to instantiate class hudson.matrix.MatrixExecutionStrategy from

{"stapler-class":["hudson.matrix.DefaultMatrixExecutionStrategyImpl","hudson.plugins.qamatrix.QAMatrixExecutionStrategyImpl"]}

at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:616)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:659)
at org.kohsuke.stapler.MetaClass$6.doDispatch(MetaClass.java:241)
at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:53)
at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:574)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:659)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:488)
at org.kohsuke.stapler.Stapler.service(Stapler.java:162)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:491)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1074)
at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:95)
at hudson.util.PluginServletFilter.doFilter(PluginServletFilter.java:87)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1065)
at hudson.security.csrf.CrumbFilter.doFilter(CrumbFilter.java:47)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1065)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:84)
at hudson.security.ChainedServletFilter.doFilter(ChainedServletFilter.java:76)
at hudson.security.HudsonFilter.doFilter(HudsonFilter.java:164)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1065)
at org.kohsuke.stapler.compression.CompressionFilter.doFilter(CompressionFilter.java:50)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1065)
at hudson.util.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:81)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1065)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:365)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:185)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:689)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:391)
at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:146)
at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:139)
at org.mortbay.jetty.Server.handle(Server.java:285)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:457)
at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:765)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:628)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:209)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:357)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:329)
at org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:475)
Caused by: java.lang.IllegalArgumentException: Failed to instantiate class hudson.matrix.MatrixExecutionStrategy from

{"stapler-class":["hudson.matrix.DefaultMatrixExecutionStrategyImpl","hudson.plugins.qamatrix.QAMatrixExecutionStrategyImpl"]}

at org.kohsuke.stapler.RequestImpl$TypePair.convertJSON(RequestImpl.java:633)
at org.kohsuke.stapler.RequestImpl.bindJSON(RequestImpl.java:377)
at org.kohsuke.stapler.RequestImpl.bindJSON(RequestImpl.java:373)
at hudson.matrix.MatrixProject.submit(MatrixProject.java:808)
at hudson.model.Job.doConfigSubmit(Job.java:991)
at hudson.model.AbstractProject.doConfigSubmit(AbstractProject.java:699)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.kohsuke.stapler.Function$InstanceFunction.invoke(Function.java:288)
at org.kohsuke.stapler.Function.bindAndInvoke(Function.java:151)
at org.kohsuke.stapler.Function.bindAndInvokeAndServeResponse(Function.java:90)
at org.kohsuke.stapler.MetaClass$1.doDispatch(MetaClass.java:111)
at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:53)
at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:574)
... 39 more
Caused by: java.lang.IllegalArgumentException: Class ["hudson.matrix.DefaultMatrixExecutionStrategyImpl","hudson.plugins.qamatrix.QAMatrixExecutionStrategyImpl"] is specified in JSON, but no such class found in classLoader hudson.PluginManager$UberClassLoader
at org.kohsuke.stapler.RequestImpl$TypePair.convertJSON(RequestImpl.java:606)
... 54 more
Caused by: java.lang.ClassNotFoundException: ["hudson.matrix.DefaultMatrixExecutionStrategyImpl","hudson.plugins.qamatrix.QAMatrixExecutionStrategyImpl"]
at hudson.PluginManager$UberClassLoader.findClass(PluginManager.java:783)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at org.kohsuke.stapler.RequestImpl$TypePair.convertJSON(RequestImpl.java:601)
... 54 more