What am I missing? Upgraded to V24 and views don't render

Flow
1

Upgraded from Vaadin 23 → Vaadin 24.

App is starting just fine, but nothing gets rendered. I tried to remove all UI views and all Spring configurations and just render a simple hello world view (with @AnonymousAllowed). Still just the loading bar.

I can see that a VaadinSession is generated, but the view class is never instantiated.

Regular servlet requests (@WebServlet) and static files are served just fine.

It’s probably a spring configuration issue, but I can’t seem to find out which one (I did check for @EnableWebMvc but it’s not used. java - Solved : Static Resources Springboot (2.6.3) and Vaadin (23.2.5) not served in production - Stack Overflow)

Anyone else experienced this or have troubleshooting tips?

Log file below.

2024-09-26T18:37:58.018Z  INFO 6209 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port 8080 (http) with context path ''
2024-09-26T18:37:58.023Z  INFO 6209 --- [  restartedMain] bc.Application                           : Started Application in 18.489 seconds (process running for 18.767)
2024-09-26T18:38:02.969Z  INFO 6209 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:02.969Z  INFO 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
2024-09-26T18:38:02.969Z TRACE 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : No MultipartResolver 'multipartResolver' declared
2024-09-26T18:38:02.969Z TRACE 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Detected org.springframework.web.servlet.i18n.AcceptHeaderLocaleResolver@5d38f8eb
2024-09-26T18:38:02.969Z TRACE 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Detected org.springframework.web.servlet.theme.FixedThemeResolver@4ad70b1f
2024-09-26T18:38:02.971Z TRACE 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Detected DefaultRequestToViewNameTranslator
2024-09-26T18:38:02.971Z TRACE 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Detected SessionFlashMapManager
2024-09-26T18:38:02.971Z DEBUG 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : enableLoggingRequestDetails='false': request parameters and headers will be masked to prevent unsafe logging of potentially sensitive data
2024-09-26T18:38:02.971Z  INFO 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 2 ms
2024-09-26T18:38:02.983Z TRACE 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : GET "/helloworld", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:02.987Z TRACE 6209 --- [nio-8080-exec-1] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.001Z  INFO 6209 --- [nio-8080-exec-1] bc.app.BCServiceInitListener             : Session Init
PathInfo: /helloworld
  host:localhost:8080
  sec-fetch-dest:document
  user-agent:Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.0 Safari/605.1.15
  upgrade-insecure-requests:1
  accept:text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
  sec-fetch-site:none
  sec-fetch-mode:navigate
  accept-language:en-US,en;q=0.9
  priority:u=0, i
  accept-encoding:gzip, deflate
  connection:keep-alive
2024-09-26T18:38:03.072Z TRACE 6209 --- [nio-8080-exec-1] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.072Z TRACE 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.072Z DEBUG 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed 200 OK, headers={masked}
2024-09-26T18:38:03.078Z TRACE 6209 --- [nio-8080-exec-2] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/static/push/vaadinPush.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.078Z TRACE 6209 --- [nio-8080-exec-2] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.078Z TRACE 6209 --- [nio-8080-exec-4] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/FlowBootstrap-BStXjIWo.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.078Z TRACE 6209 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/generated-flow-imports-CaNKToDw.css", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.079Z TRACE 6209 --- [nio-8080-exec-4] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.079Z TRACE 6209 --- [nio-8080-exec-5] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/react-utils-D_MlSXfo-UoRpHi8k.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.079Z TRACE 6209 --- [nio-8080-exec-3] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.079Z TRACE 6209 --- [nio-8080-exec-5] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.079Z TRACE 6209 --- [nio-8080-exec-6] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/copilot-init-step2-D2eVjgmc-BZ8xCdtx.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.079Z TRACE 6209 --- [nio-8080-exec-6] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.081Z TRACE 6209 --- [nio-8080-exec-7] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/state-DOkKKpWv-C8xNvuud.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.082Z TRACE 6209 --- [nio-8080-exec-7] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.082Z TRACE 6209 --- [nio-8080-exec-3] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.082Z TRACE 6209 --- [nio-8080-exec-4] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.082Z TRACE 6209 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.082Z TRACE 6209 --- [nio-8080-exec-4] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.082Z TRACE 6209 --- [nio-8080-exec-6] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.082Z TRACE 6209 --- [nio-8080-exec-5] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.082Z TRACE 6209 --- [nio-8080-exec-6] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.082Z DEBUG 6209 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.082Z DEBUG 6209 --- [nio-8080-exec-4] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.082Z DEBUG 6209 --- [nio-8080-exec-6] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.082Z TRACE 6209 --- [nio-8080-exec-5] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.082Z DEBUG 6209 --- [nio-8080-exec-5] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.083Z TRACE 6209 --- [nio-8080-exec-7] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.083Z TRACE 6209 --- [nio-8080-exec-7] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.083Z DEBUG 6209 --- [nio-8080-exec-7] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.083Z TRACE 6209 --- [nio-8080-exec-8] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/indexhtml-B2odIL8P.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.084Z TRACE 6209 --- [nio-8080-exec-8] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.084Z TRACE 6209 --- [nio-8080-exec-9] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/overlay-monkeypatch-tiv0Sndr-CaApAQKH.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.084Z TRACE 6209 --- [io-8080-exec-10] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/icons-DpnnuXfg-bmvw6wCd.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.084Z TRACE 6209 --- [nio-8080-exec-9] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.084Z TRACE 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/copilot-notification-CUWNmpXC-Bdq_QiG4.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.084Z TRACE 6209 --- [io-8080-exec-10] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.085Z TRACE 6209 --- [nio-8080-exec-1] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.085Z TRACE 6209 --- [nio-8080-exec-8] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.085Z TRACE 6209 --- [nio-8080-exec-8] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.085Z DEBUG 6209 --- [nio-8080-exec-8] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.086Z TRACE 6209 --- [nio-8080-exec-1] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.086Z TRACE 6209 --- [nio-8080-exec-6] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/copilot-log-plugin-DqW4LFpS-BdG1ZlpY.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.086Z TRACE 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.086Z DEBUG 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.086Z TRACE 6209 --- [io-8080-exec-10] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.086Z TRACE 6209 --- [io-8080-exec-10] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.086Z DEBUG 6209 --- [io-8080-exec-10] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.088Z TRACE 6209 --- [nio-8080-exec-9] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.088Z TRACE 6209 --- [nio-8080-exec-9] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.088Z DEBUG 6209 --- [nio-8080-exec-9] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.088Z TRACE 6209 --- [nio-8080-exec-6] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.088Z TRACE 6209 --- [nio-8080-exec-5] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/copilot-info-plugin-CnccKHsK-DkLSkJMQ.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.088Z TRACE 6209 --- [nio-8080-exec-4] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/base-panel-BWfqXAMS-B5PaoAdK.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.088Z TRACE 6209 --- [nio-8080-exec-5] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.088Z TRACE 6209 --- [nio-8080-exec-4] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.088Z TRACE 6209 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/copilot-features-plugin-tTmmpCLZ-DIK3bo6P.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.088Z TRACE 6209 --- [nio-8080-exec-3] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.088Z TRACE 6209 --- [nio-8080-exec-6] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.089Z TRACE 6209 --- [nio-8080-exec-6] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.089Z TRACE 6209 --- [nio-8080-exec-4] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.089Z DEBUG 6209 --- [nio-8080-exec-6] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.089Z TRACE 6209 --- [nio-8080-exec-4] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.089Z TRACE 6209 --- [nio-8080-exec-5] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.089Z TRACE 6209 --- [nio-8080-exec-5] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.089Z TRACE 6209 --- [nio-8080-exec-3] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.089Z DEBUG 6209 --- [nio-8080-exec-4] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.089Z TRACE 6209 --- [nio-8080-exec-7] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/copilot-feedback-plugin-9cDu751o-BA9mQ931.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.089Z TRACE 6209 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.089Z DEBUG 6209 --- [nio-8080-exec-5] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.089Z DEBUG 6209 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.089Z TRACE 6209 --- [nio-8080-exec-7] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.090Z TRACE 6209 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/copilot-shortcuts-plugin-DOgmp4xR-BPYMs5O1.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.090Z TRACE 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/copilot-global-vars-later-CmEQcCRy-DhJ_Mduk.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.090Z TRACE 6209 --- [nio-8080-exec-3] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.091Z TRACE 6209 --- [nio-8080-exec-1] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.091Z TRACE 6209 --- [nio-8080-exec-7] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.091Z TRACE 6209 --- [nio-8080-exec-7] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.091Z DEBUG 6209 --- [nio-8080-exec-7] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.091Z TRACE 6209 --- [nio-8080-exec-9] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/static/push/vaadinPush.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.092Z TRACE 6209 --- [nio-8080-exec-3] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.092Z TRACE 6209 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.092Z TRACE 6209 --- [nio-8080-exec-9] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.092Z TRACE 6209 --- [nio-8080-exec-1] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.092Z TRACE 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.092Z TRACE 6209 --- [io-8080-exec-10] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/generated-flow-imports-DOwMQd57.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.092Z DEBUG 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.092Z DEBUG 6209 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.092Z TRACE 6209 --- [io-8080-exec-10] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.093Z TRACE 6209 --- [io-8080-exec-10] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.093Z TRACE 6209 --- [io-8080-exec-10] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.093Z DEBUG 6209 --- [io-8080-exec-10] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.093Z TRACE 6209 --- [nio-8080-exec-6] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/indexhtml-B2odIL8P.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.095Z TRACE 6209 --- [nio-8080-exec-6] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.095Z TRACE 6209 --- [nio-8080-exec-6] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.095Z TRACE 6209 --- [nio-8080-exec-6] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.095Z DEBUG 6209 --- [nio-8080-exec-6] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.098Z TRACE 6209 --- [nio-8080-exec-2] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.098Z TRACE 6209 --- [nio-8080-exec-2] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.098Z TRACE 6209 --- [nio-8080-exec-9] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.098Z DEBUG 6209 --- [nio-8080-exec-2] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.098Z TRACE 6209 --- [nio-8080-exec-9] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.098Z DEBUG 6209 --- [nio-8080-exec-9] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.143Z TRACE 6209 --- [nio-8080-exec-5] o.s.web.servlet.DispatcherServlet        : GET "/?v-r=init&location=helloworld&query=", parameters={masked}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.143Z TRACE 6209 --- [nio-8080-exec-5] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.144Z  INFO 6209 --- [nio-8080-exec-5] bc.app.BCServiceInitListener             : Session Init
PathInfo: /
  host:localhost:8080
  sec-fetch-dest:empty
  user-agent:Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.0 Safari/605.1.15
  accept:*/*
  referer:http://localhost:8080/helloworld
  sec-fetch-site:same-origin
  sec-fetch-mode:cors
  accept-language:en-US,en;q=0.9
  priority:u=3, i
  accept-encoding:gzip, deflate
  connection:keep-alive
2024-09-26T18:38:03.199Z TRACE 6209 --- [nio-8080-exec-5] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.199Z TRACE 6209 --- [nio-8080-exec-5] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.199Z DEBUG 6209 --- [nio-8080-exec-5] o.s.web.servlet.DispatcherServlet        : Completed 200 OK, headers={masked}
2024-09-26T18:38:03.201Z TRACE 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/FlowBootstrap-BStXjIWo.js", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.201Z TRACE 6209 --- [nio-8080-exec-1] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.202Z TRACE 6209 --- [nio-8080-exec-1] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.202Z TRACE 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.202Z DEBUG 6209 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2024-09-26T18:38:03.204Z TRACE 6209 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : GET "/VAADIN/build/generated-flow-imports-CaNKToDw.css", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2024-09-26T18:38:03.204Z TRACE 6209 --- [nio-8080-exec-3] o.s.w.s.mvc.ServletForwardingController  : Applying default cacheSeconds=-1
2024-09-26T18:38:03.205Z TRACE 6209 --- [nio-8080-exec-3] o.s.w.s.mvc.ServletForwardingController  : Forwarded to servlet [springServlet] in ServletForwardingController 'vaadinForwardingController'
2024-09-26T18:38:03.205Z TRACE 6209 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : No view rendering, null ModelAndView returned.
2024-09-26T18:38:03.205Z DEBUG 6209 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : Completed 304 NOT_MODIFIED, headers={masked}
2

Just to be sure : did you also upgrade Spring Boot to 3.2?

3

Correct. I downloaded the Vaadin Start App and used the pom as the starting point.

    <properties>
        <java.version>21</java.version>
        <vaadin.version>24.4.12</vaadin.version>
    </properties>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.2.9</version>
    </parent>
4

Any errors in the browser console?
You may try to run mvn vaadin:clean-frontend and then start the application

5

Thanks I tried to clean the frontend and also emptied caches.

I am seeing an error in the frontend - “Cannot define multiple custom elements with the same tag name”. It’s not showing what the tag names are.

I removed all my own UI components and scripts but that doesn’t seem to have an effect.

Screenshot 2024-09-26 at 3.06.56 PM
Screenshot 2024-09-26 at 3.06.56 PM1732×278 37.5 KB

This is the code line where it happens

Screenshot 2024-09-26 at 3.09.28 PM
Screenshot 2024-09-26 at 3.09.28 PM1736×1068 171 KB

6

Weird that the tag name is not logged.
Does the application perhaps use some third party add-on?

7

Outcommented all the 3rd party components in the POM and also cleaned Vaadin front-end again.

Tried with Firefox and this time I got a little more detail:

Screenshot 2024-09-26 at 4.32.55 PM
Screenshot 2024-09-26 at 4.32.55 PM2248×370 103 KB

8

I had toggle-button v.2.0.0 in the pom, but it was out commented. I did several maven project updates, several vaadin:clean-frontend and cleaned the browser cache with no difference.

Inspired by this post: spring boot - Vaadin 24 NotSupportedError vaadin-checkbox - Stack Overflow, I re-added the toggle-button to the pom and changed the version to 3.0.0 and recompiled.

That seemed to fix it and I could launch the frontend without the
“multiple custom elements” error in the browser.

Will continue with some more tests tomorrow.

9

We had the same issue when moving from Vaadin 23 to 24.
Set vaadin.react.enable=false and vaadin.reactEnable=false and did excluded flow-react in our pom.

The fix was to update all Add-Ons to the newest version and then it worked for us :slight_smile: (and enabled react again)

10

Good to know, thanks Leander.

11

Thanks for your help @marcoc_753. It was in fact the toggle-button add-on that caused the issue.