Getting this exception

com.haulmont.cuba.core.global.RemoteException:

javax.persistence.NonUniqueResultException: More than one result was returned from Query.getSingleResult()
at com.haulmont.cuba.core.sys.ServiceInterceptor.aroundInvoke(ServiceInterceptor.java:129)
at sun.reflect.GeneratedMethodAccessor125.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:629)
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:618)
at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:70)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:168)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
at com.sun.proxy.$Proxy213.commit(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.haulmont.cuba.core.sys.remoting.LocalServiceInvokerImpl.invoke(LocalServiceInvokerImpl.java:94)
at com.haulmont.cuba.web.sys.remoting.LocalServiceProxy$LocalServiceInvocationHandler.invoke(LocalServiceProxy.java:154)
at com.sun.proxy.$Proxy29.commit(Unknown Source)
at com.haulmont.cuba.client.sys.DataManagerClientImpl.commit(DataManagerClientImpl.java:96)
at com.haulmont.cuba.gui.data.impl.GenericDataSupplier.commit(GenericDataSupplier.java:90)
at com.haulmont.cuba.gui.data.impl.DsContextImpl.commit(DsContextImpl.java:165)
at com.haulmont.cuba.gui.components.EditorWindowDelegate.commit(EditorWindowDelegate.java:283)
at com.haulmont.cuba.web.gui.WebWindow$Editor.commitAndClose(WebWindow.java:1755)
at com.haulmont.cuba.gui.components.AbstractEditor.commitAndClose(AbstractEditor.java:109)
at com.haulmont.cuba.gui.components.EditorWindowDelegate$2.actionPerform(EditorWindowDelegate.java:102)
at com.haulmont.cuba.web.gui.components.WebButton.performAction(WebButton.java:44)
at com.haulmont.cuba.web.gui.components.WebButton.lambda$new$61446b05$1(WebButton.java:36)
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:510)
at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:200)
at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:163)
at com.vaadin.server.AbstractClientConnector.fireEvent(AbstractClientConnector.java:1037)
at com.vaadin.ui.Button.fireClick(Button.java:377)
at com.haulmont.cuba.web.toolkit.ui.CubaButton.fireClick(CubaButton.java:54)
at com.vaadin.ui.Button$1.click(Button.java:54)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.vaadin.server.ServerRpcManager.applyInvocation(ServerRpcManager.java:158)
at com.vaadin.server.ServerRpcManager.applyInvocation(ServerRpcManager.java:119)
at com.vaadin.server.communication.ServerRpcHandler.handleInvocation(ServerRpcHandler.java:444)
at com.vaadin.server.communication.ServerRpcHandler.handleInvocations(ServerRpcHandler.java:409)
at com.vaadin.server.communication.ServerRpcHandler.handleRpc(ServerRpcHandler.java:274)
at com.vaadin.server.communication.UidlRequestHandler.synchronizedHandleRequest(UidlRequestHandler.java:90)
at com.vaadin.server.SynchronizedRequestHandler.handleRequest(SynchronizedRequestHandler.java:41)
at com.vaadin.server.VaadinService.handleRequest(VaadinService.java:1435)
at com.vaadin.server.VaadinServlet.service(VaadinServlet.java:361)
at com.haulmont.cuba.web.sys.CubaApplicationServlet.serviceAppRequest(CubaApplicationServlet.java:300)
at com.haulmont.cuba.web.sys.CubaApplicationServlet.service(CubaApplicationServlet.java:191)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.CompositeFilter$VirtualFilterChain.doFilter(CompositeFilter.java:107)
at org.springframework.web.filter.CompositeFilter.doFilter(CompositeFilter.java:73)
at com.haulmont.cuba.web.sys.CubaHttpFilter.doFilter(CubaHttpFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:478)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:650)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)

Hi,
Could you please format your topic with code block for stactrace and provide a context: code, your steps, version of the platform. Without context it is really hard to help you.