Deploying on tomcat problem

You just need to add an empty constructor, as the exception message says, and a super() call should be placed as well (in both constructors).

public VaadinUI()
{
    super();
}

That was the frist thing i tried and i got 

12:29:36,204 SEVERE [com.vaadin.server.DefaultErrorHandler] (default task-12) : com.vaadin.event.ListenerMethod$MethodException: Invocation of method uriFragmentChanged in com.vaadin.navigator.Navigator$UriFragmentManager failed.

    at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:528)

    at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:198)

    at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:161)

    at com.vaadin.server.Page.fireEvent(Page.java:603)

    at com.vaadin.server.Page.setUriFragment(Page.java:596)

    at com.vaadin.server.Page.setUriFragment(Page.java:616)

    at at.e.screen.hello.gui.LoginPage$1.buttonClick(LoginPage.java:44)

    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

    at java.lang.reflect.Method.invoke(Method.java:498)

    at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:508)

    at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:198)

    at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:161)

    at com.vaadin.server.AbstractClientConnector.fireEvent(AbstractClientConnector.java:1008)

    at com.vaadin.ui.Button.fireClick(Button.java:377)

    at com.vaadin.ui.Button$1.click(Button.java:54)

    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

    at java.lang.reflect.Method.invoke(Method.java:498)

    at com.vaadin.server.ServerRpcManager.applyInvocation(ServerRpcManager.java:158)

    at com.vaadin.server.ServerRpcManager.applyInvocation(ServerRpcManager.java:118)

    at com.vaadin.server.communication.ServerRpcHandler.handleInvocations(ServerRpcHandler.java:408)

    at com.vaadin.server.communication.ServerRpcHandler.handleRpc(ServerRpcHandler.java:273)

    at com.vaadin.server.communication.UidlRequestHandler.synchronizedHandleRequest(UidlRequestHandler.java:79)

    at com.vaadin.server.SynchronizedRequestHandler.handleRequest(SynchronizedRequestHandler.java:41)

    at com.vaadin.server.VaadinService.handleRequest(VaadinService.java:1409)

    at com.vaadin.server.VaadinServlet.service(VaadinServlet.java:364)

    at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)

    at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85)

    at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:129)

    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)

    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)

    at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)

    at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)

    at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:87)

    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)

    at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)

    at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)

    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)

    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)

    at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)

    at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)

    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)

    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)

    at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)

    at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)

    at org.springframework.boot.web.support.ErrorPageFilter.doFilter(ErrorPageFilter.java:119)

    at org.springframework.boot.web.support.ErrorPageFilter.access$000(ErrorPageFilter.java:61)

    at org.springframework.boot.web.support.ErrorPageFilter$1.doFilterInternal(ErrorPageFilter.java:94)

    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)

    at org.springframework.boot.web.support.ErrorPageFilter.doFilter(ErrorPageFilter.java:112)

    at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)

    at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)

    at io.undertow.servlet.handlers.FilterHandler.handleRequest(FilterHandler.java:84)

    at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)

    at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)

    at org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)

    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)

    at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:131)

    at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:57)

    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)

    at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46)

    at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64)

    at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:60)

    at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:77)

    at io.undertow.security.handlers.NotificationReceiverHandler.handleRequest(NotificationReceiverHandler.java:50)

    at io.undertow.security.handlers.AbstractSecurityContextAssociationHandler.handleRequest(AbstractSecurityContextAssociationHandler.java:43)

    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)

    at org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)

    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)

    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)

    at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:285)

    at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:264)

    at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:81)

    at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:175)

    at io.undertow.server.Connectors.executeRootHandler(Connectors.java:202)

    at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:792)

    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)

    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)

    at java.lang.Thread.run(Thread.java:745)

Caused by: java.lang.NullPointerException

    at at.e.screen.hello.gui.SecurePage.listCustomers(SecurePage.java:83)

    at at.e.screen.hello.gui.SecurePage.<init>(SecurePage.java:54)

    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)

    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)

    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)

    at java.lang.Class.newInstance(Class.java:442)

    at com.vaadin.navigator.Navigator$ClassBasedViewProvider.getView(Navigator.java:340)

    at com.vaadin.navigator.Navigator.navigateTo(Navigator.java:559)

    at com.vaadin.navigator.Navigator$UriFragmentManager.uriFragmentChanged(Navigator.java:145)

    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

    at java.lang.reflect.Method.invoke(Method.java:498)

    at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:508)

    ... 81 more

You should fix nullpointer access in your code:

Caused by: java.lang.NullPointerException
 
    at at.e.screen.hello.gui.SecurePage.listCustomers(SecurePage.java:83)

NullPointerExeption is coused by empty jpa repository(LocationRepository) which is in this case not autowired. 

@Autowired

        public VaadinUI(LocationRepository repo) {

            super();

            this.locationRepository = repo;

        }

Non-arg constructor is initialized

public VaadinUI(){

            super();

        }

Is there another way to wire jpa repositories with vaadinUI?
i followed this tutorial https://spring.io/guides/gs/crud-with-vaadin/

Thanks 

so what happens if you autowire LocationRepository directly?

@Autowired
public LocationRepository locationRepository;

you also should avoid the static modifier in your variables, which typically leads to problems here...

public static Customer AUTH;
public static LocationRepository locationRepository;
 

Try making your servlet extend SpringVaadinServlet instead of VaadinServlet; BTW if you are using vaadin spring boot starter i think you don't need to extend the servlet.

HTH
Marco

Thanks Marco, extending a SpringVaadinServlet solved the problem.
Thanks a lot