Collaborator upgrade to 11 error

while upgrading from 10 to 11 Collaborator, gettng error while upgrading database. 

2017-03-16 23:42:13,881 INFO http-nio-8082-exec-12 com.smartbear.ccollab.rpc.RpcGwtServlet$GwtInvocationHandler - Error invoking
com.smartbear.ccollab.service.api.v7001.ServiceException: A critical error occurred while upgrading the database: null Please contact customer support.
at com.smartbear.ccollab.rpc.RpcGwtServlet$GwtInvocationHandler.initializeServer(RpcGwtServlet.java:963)
at com.smartbear.ccollab.service.impl.unversioned.UnversionedClientApiImpl.initializeServer(UnversionedClientApiImpl.java:229)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.smartbear.ccollab.rpc.RpcGwtServlet$GwtInvocationHandler.invoke(RpcGwtServlet.java:423)
at com.smartbear.util.DelegatingInvocationHandler.invoke(DelegatingInvocationHandler.java:28)
at com.sun.proxy.$Proxy10.initializeServer(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.smartbear.ccollab.service.impl.ServerNotInitializedExceptionProxy.invoke(ServerNotInitializedExceptionProxy.java:41)
at com.smartbear.util.DelegatingInvocationHandler.invoke(DelegatingInvocationHandler.java:28)
at com.smartbear.ccollab.rpc.RpcGwtServlet$LoggingInvocationHandler.invoke(RpcGwtServlet.java:1263)
at com.smartbear.util.DelegatingInvocationHandler.invoke(DelegatingInvocationHandler.java:28)
at com.smartbear.ccollab.rpc.RpcGwtServlet$TimingInvocationHandler.invoke(RpcGwtServlet.java:1322)
at com.smartbear.util.DelegatingInvocationHandler.invoke(DelegatingInvocationHandler.java:28)
at com.sun.proxy.$Proxy10.initializeServer(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.smartbear.ccollab.service.impl.ExposeExceptionsProxy.invoke(ExposeExceptionsProxy.java:29)
at com.sun.proxy.$Proxy10.initializeServer(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:587)
at com.smartbear.ccollab.rpc.RpcGwtServlet.processCall(RpcGwtServlet.java:274)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:373)
at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)