Creating a representation gives a NullPointerException

[TristanDelaigue]

Hello,

I'm trying to install and run SysON following the developer guide (https://doc.mbse-syson.org/syson/v2026.3.0/developer-guide/index.html). I followed the steps and managed to build the application and launch it, and everything seems to work properly, except when I try to create a representation (any kind except requirement table view), in which case it gives the following error:

java.util.concurrent.ExecutionException: java.lang.NullPointerException: Cannot invoke "org.eclipse.sirius.components.view.diagram.DiagramStyleDescription.getBackground()" because "diagramStyleDescription" is null
	at java.base/java.util.concurrent.FutureTask.report(FutureTask.java:122) ~[na:na]
	at java.base/java.util.concurrent.FutureTask.get(FutureTask.java:191) ~[na:na]
	at org.eclipse.sirius.components.collaborative.editingcontext.EditingContextEventProcessor.handle(EditingContextEventProcessor.java:135) ~[sirius-components-collaborative-2026.3.0.jar:2026.3.0]
	at org.eclipse.sirius.components.collaborative.editingcontext.EditingContextEventProcessorRegistry.lambda$dispatchEvent$1(EditingContextEventProcessorRegistry.java:97) ~[sirius-components-collaborative-2026.3.0.jar:2026.3.0]
	at java.base/java.util.Optional.map(Optional.java:260) ~[na:na]
	at org.eclipse.sirius.components.collaborative.editingcontext.EditingContextEventProcessorRegistry.dispatchEvent(EditingContextEventProcessorRegistry.java:97) ~[sirius-components-collaborative-2026.3.0.jar:2026.3.0]
	at org.eclipse.sirius.web.application.editingcontext.services.EditingContextDispatcher.dispatchMutation(EditingContextDispatcher.java:107) ~[sirius-web-application-2026.3.0.jar:2026.3.0]
	at org.eclipse.sirius.web.application.representation.controllers.MutationCreateRepresentationDataFetcher.get(MutationCreateRepresentationDataFetcher.java:52) ~[sirius-web-application-2026.3.0.jar:2026.3.0]
	at org.eclipse.sirius.web.application.representation.controllers.MutationCreateRepresentationDataFetcher.get(MutationCreateRepresentationDataFetcher.java:33) ~[sirius-web-application-2026.3.0.jar:2026.3.0]
	at graphql.execution.ExecutionStrategy.invokeDataFetcher(ExecutionStrategy.java:510) ~[graphql-java-24.3.jar:na]
	at graphql.execution.ExecutionStrategy.fetchField(ExecutionStrategy.java:464) ~[graphql-java-24.3.jar:na]
	at graphql.execution.ExecutionStrategy.fetchField(ExecutionStrategy.java:404) ~[graphql-java-24.3.jar:na]
	at graphql.execution.ExecutionStrategy.resolveFieldWithInfo(ExecutionStrategy.java:363) ~[graphql-java-24.3.jar:na]
	at graphql.execution.AsyncSerialExecutionStrategy.resolveSerialField(AsyncSerialExecutionStrategy.java:73) ~[graphql-java-24.3.jar:na]
	at graphql.execution.AsyncSerialExecutionStrategy.lambda$execute$0(AsyncSerialExecutionStrategy.java:57) ~[graphql-java-24.3.jar:na]
	at graphql.execution.Async.eachSequentiallyPolymorphicImpl(Async.java:329) ~[graphql-java-24.3.jar:na]
	at graphql.execution.Async.eachSequentially(Async.java:317) ~[graphql-java-24.3.jar:na]
	at graphql.execution.AsyncSerialExecutionStrategy.execute(AsyncSerialExecutionStrategy.java:52) ~[graphql-java-24.3.jar:na]
	at graphql.execution.Execution.executeOperation(Execution.java:205) ~[graphql-java-24.3.jar:na]
	at graphql.execution.Execution.execute(Execution.java:124) ~[graphql-java-24.3.jar:na]
	at graphql.GraphQL.execute(GraphQL.java:549) ~[graphql-java-24.3.jar:na]
	at graphql.GraphQL.lambda$parseValidateAndExecute$13(GraphQL.java:479) ~[graphql-java-24.3.jar:na]
	at java.base/java.util.concurrent.CompletableFuture.uniComposeStage(CompletableFuture.java:1187) ~[na:na]
	at java.base/java.util.concurrent.CompletableFuture.thenCompose(CompletableFuture.java:2341) ~[na:na]
	at graphql.EngineRunningState.compose(EngineRunningState.java:87) ~[graphql-java-24.3.jar:na]
	at graphql.GraphQL.parseValidateAndExecute(GraphQL.java:474) ~[graphql-java-24.3.jar:na]
	at graphql.GraphQL.lambda$executeAsync$9(GraphQL.java:434) ~[graphql-java-24.3.jar:na]
	at java.base/java.util.concurrent.CompletableFuture.uniComposeStage(CompletableFuture.java:1187) ~[na:na]
	at java.base/java.util.concurrent.CompletableFuture.thenCompose(CompletableFuture.java:2341) ~[na:na]
	at graphql.EngineRunningState.compose(EngineRunningState.java:87) ~[graphql-java-24.3.jar:na]
	at graphql.GraphQL.lambda$executeAsync$10(GraphQL.java:423) ~[graphql-java-24.3.jar:na]
	at graphql.EngineRunningState.call(EngineRunningState.java:198) ~[graphql-java-24.3.jar:na]
	at graphql.GraphQL.executeAsync(GraphQL.java:416) ~[graphql-java-24.3.jar:na]
	at graphql.GraphQL.execute(GraphQL.java:359) ~[graphql-java-24.3.jar:na]
	at org.eclipse.sirius.components.graphql.controllers.GraphQLController.performRequest(GraphQLController.java:154) ~[sirius-components-graphql-2026.3.0.jar:2026.3.0]
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103) ~[na:na]
	at java.base/java.lang.reflect.Method.invoke(Method.java:580) ~[na:na]
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:258) ~[spring-web-6.2.16.jar:6.2.16]
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:191) ~[spring-web-6.2.16.jar:6.2.16]
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:118) ~[spring-webmvc-6.2.16.jar:6.2.16]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:991) ~[spring-webmvc-6.2.16.jar:6.2.16]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:896) ~[spring-webmvc-6.2.16.jar:6.2.16]
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-6.2.16.jar:6.2.16]
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1089) ~[spring-webmvc-6.2.16.jar:6.2.16]
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:979) ~[spring-webmvc-6.2.16.jar:6.2.16]
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1014) ~[spring-webmvc-6.2.16.jar:6.2.16]
	at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:914) ~[spring-webmvc-6.2.16.jar:6.2.16]
	at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:590) ~[tomcat-embed-core-10.1.52.jar:6.0]
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:885) ~[spring-webmvc-6.2.16.jar:6.2.16]
	at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:658) ~[tomcat-embed-core-10.1.52.jar:6.0]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:138) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51) ~[tomcat-embed-websocket-10.1.52.jar:10.1.52]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:138) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-6.2.16.jar:6.2.16]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.2.16.jar:6.2.16]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:138) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-6.2.16.jar:6.2.16]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.2.16.jar:6.2.16]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:138) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.springframework.web.filter.ServerHttpObservationFilter.doFilterInternal(ServerHttpObservationFilter.java:110) ~[spring-web-6.2.16.jar:6.2.16]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.2.16.jar:6.2.16]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:138) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-6.2.16.jar:6.2.16]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.2.16.jar:6.2.16]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:138) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:165) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:88) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:492) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:113) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:83) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:72) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:399) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:903) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1775) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:973) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:491) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:63) ~[tomcat-embed-core-10.1.52.jar:10.1.52]
	at java.base/java.lang.Thread.run(Thread.java:1583) ~[na:na]
Caused by: java.lang.NullPointerException: Cannot invoke "org.eclipse.sirius.components.view.diagram.DiagramStyleDescription.getBackground()" because "diagramStyleDescription" is null
	at org.eclipse.sirius.components.view.emf.diagram.StylesFactory.createDiagramStyle(StylesFactory.java:131) ~[sirius-components-view-emf-2026.3.0.jar:2026.3.0]
	at org.eclipse.sirius.components.view.emf.diagram.ViewDiagramDescriptionConverter.lambda$convert$6(ViewDiagramDescriptionConverter.java:154) ~[sirius-components-view-emf-2026.3.0.jar:2026.3.0]
	at org.eclipse.sirius.components.diagrams.components.DiagramComponent.render(DiagramComponent.java:55) ~[sirius-components-diagrams-2026.3.0.jar:2026.3.0]
	at org.eclipse.sirius.components.representations.BaseRenderer.renderComponent(BaseRenderer.java:212) ~[sirius-components-representations-2026.3.0.jar:2026.3.0]
	at org.eclipse.sirius.components.representations.BaseRenderer.renderElement(BaseRenderer.java:133) ~[sirius-components-representations-2026.3.0.jar:2026.3.0]
	at org.eclipse.sirius.components.diagrams.renderer.DiagramRenderer.render(DiagramRenderer.java:71) ~[sirius-components-diagrams-2026.3.0.jar:2026.3.0]
	at org.eclipse.sirius.components.collaborative.diagrams.DiagramCreationService.doRender(DiagramCreationService.java:173) ~[sirius-components-collaborative-diagrams-2026.3.0.jar:2026.3.0]
	at org.eclipse.sirius.components.collaborative.diagrams.DiagramCreationService.create(DiagramCreationService.java:109) ~[sirius-components-collaborative-diagrams-2026.3.0.jar:2026.3.0]
	at org.eclipse.sirius.components.collaborative.diagrams.handlers.CreateDiagramEventHandler.handle(CreateDiagramEventHandler.java:117) ~[sirius-components-collaborative-diagrams-2026.3.0.jar:2026.3.0]
	at org.eclipse.sirius.components.collaborative.editingcontext.InputDispatcher.handleInput(InputDispatcher.java:112) ~[sirius-components-collaborative-2026.3.0.jar:2026.3.0]
	at org.eclipse.sirius.components.collaborative.editingcontext.InputDispatcher.dispatch(InputDispatcher.java:86) ~[sirius-components-collaborative-2026.3.0.jar:2026.3.0]
	at org.eclipse.sirius.components.collaborative.editingcontext.EditingContextEventProcessor.lambda$handle$2(EditingContextEventProcessor.java:132) ~[sirius-components-collaborative-2026.3.0.jar:2026.3.0]
	at org.eclipse.sirius.components.web.concurrent.DelegatingRequestContextRunnable.run(DelegatingRequestContextRunnable.java:40) ~[sirius-components-web-2026.3.0.jar:2026.3.0]
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:572) ~[na:na]
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317) ~[na:na]
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144) ~[na:na]
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642) ~[na:na]
	... 1 common frames omitted

I have tried going back to the version of the code of the last stable release (2026.3.0) instead of the last commit, but the error was the same.

Any ideas on why this happens and how to fix it ?

Thank you very much

[AxelRICHARD]

Hello Tristan,

The code in SysON using org.eclipse.sirius.components.view.diagram.DiagramStyleDescription.getBackground() has been introduced very recently, while bumping to Sirius Web 2026.3.1.

In your stack trace, you seem to use Sirius Web 2026.3.0.

So there are several options here:

• you stay on the commit corresponding to the last stable release 2026.3.0, then you do your developments
• you want to follow the latest developments and you are on top on the main branch, you do your developments and you rebase them frequently to stay up-to-date.

In both cases, in Eclipse STS, a Maven > Update Projects (as described in https://doc.mbse-syson.org/syson/v2026.3.0/developer-guide/index.html#_backend_2) should help you to retrieve the version of Sirius Web corresponding to the commit of SysON you have checkouted.

Regards,

[TristanDelaigue]

Thank you for your reply,

Unfortunately, even after following the steps, I still have the same error.
I have tried creating a new workspace and cloning the code on the v2026.3.0 branch, and following the process again from scratch, but I get the same result.

What I find especially strange is that the error comes from org.eclipse.sirius.components.views.emf.diagram.StylesFactory in sirius-components-views-emf-2026.3.0.jar where the diagramStyleDescription.getBackground() appears. But the file seems to be different from the one in the sirius web repository on the v2026.3.0 branch (https://github.com/eclipse-sirius/sirius-web/blob/v2026.3.0/packages/view/backend/sirius-components-view-emf/src/main/java/org/eclipse/sirius/components/view/emf/diagram/StylesFactory.java). In fact, the file that is called when I launch the application seems to corresponds to the v2026.3.1 version of the same file (https://github.com/eclipse-sirius/sirius-web/blob/v2026.3.1/packages/view/backend/sirius-components-view-emf/src/main/java/org/eclipse/sirius/components/view/emf/diagram/StylesFactory.java).

Another thing I tried was to create new empty java application, with the SysOn dependencies in the pom.xml (on version 2026.3.0), and when I launched it, I got the same error when trying to create a representation (even if I didn't clone the code for this application)

Thank you very much once again,

[AxelRICHARD]

It's strange indeed. You can try to execute your maven commands on a fresh new local repository (different than the default one in your $HOME/.m2) with the maven.repo.local option. For example, on the SysON root folder, just do mvn clean verify -Dmaven.repo.local=/path/to/your/new/local/repo (and don't forget to also copy your settings.xml in this new maven local repo).