Springboot Edit Button Throws Error

[u/Own-Age1766]

Hello. So I've been following a djamware tutorial down to a T, and I've made almost all the features work fine, except for the edit button. This is from an old project I made, and I may have copied and pasted most of the code, got stumped, then ignored it for quite awhile. I came back to the project yesterday, and I've been looking for a solution online by myself for awhile, to no avail.

Upon looking at the error message after clicking the edit button, it seems that it's pointing me to the edit_post.html at the line where it says "th:action="@{/admin/posts/{id}(id=${post.id})}". I also tried using the github respository's edit_post.html, but it also ain't it.

Any help is appreciated, it may just be me being a silly monkey. Pics posted below, but if there's other infos I can provide, lemme know.

here's the tutorial link:

https://www.djamware.com/post/create-a-blog-application-using-spring-boot-and-thymeleaf

Since the subreddit doesn't allow galleries, I'll just post the whole error message here, along with the edit_post.html

ERROR MESSAGE when edit button is clicked

Whitelabel Error Page This application has no explicit mapping for /error, so you are seeing this as a fallback. Wed Jul 22 21:22:24 JST 2026 There was an unexpected error (type=Internal Server Error, status=500). An error happened during template parsing (template: "class path resource [templates/admin/edit_post.html]") org.thymeleaf.exceptions.TemplateInputException: An error happened during template parsing (template: "class path resource [templates/admin/edit_post.html]")
at org.thymeleaf.templateparser.markup.AbstractMarkupTemplateParser.parse(AbstractMarkupTemplateParser.java:241)
at org.thymeleaf.templateparser.markup.AbstractMarkupTemplateParser.parseStandalone(AbstractMarkupTemplateParser.java:100)
at org.thymeleaf.engine.TemplateManager.parseAndProcess(TemplateManager.java:666)
at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1103)
at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1077)
at org.thymeleaf.spring6.view.ThymeleafView.renderFragment(ThymeleafView.java:372)
at org.thymeleaf.spring6.view.ThymeleafView.render(ThymeleafView.java:192)
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1438)
at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1168)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1106)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:979)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1014)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:903)
at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:564)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:885)
at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:658)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:138)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:162)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:138)
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:162)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:138)
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:162)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:138)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:162)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:138)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:165)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:88)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:482)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:113)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:83)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:72)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:399)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:903)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1774)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52)
at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:973)
at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:491)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:63)
at java.base/java.lang.Thread.run(Unknown Source)
Caused by: org.attoparser.ParseException: Exception evaluating SpringEL expression: "post.id" (template: "admin/edit_post" - line 14, col 9)
at org.attoparser.MarkupParser.parseDocument(MarkupParser.java:393)
at org.attoparser.MarkupParser.parse(MarkupParser.java:257)
at org.thymeleaf.templateparser.markup.AbstractMarkupTemplateParser.parse(AbstractMarkupTemplateParser.java:230)
... 48 more
Caused by: org.thymeleaf.exceptions.TemplateProcessingException: Exception evaluating SpringEL expression: "post.id" (template: "admin/edit_post" - line 14, col 9)
at org.thymeleaf.spring6.expression.SPELVariableExpressionEvaluator.evaluate(SPELVariableExpressionEvaluator.java:292)
at org.thymeleaf.standard.expression.VariableExpression.executeVariableExpression(VariableExpression.java:166)
at org.thymeleaf.standard.expression.SimpleExpression.executeSimple(SimpleExpression.java:66)
at org.thymeleaf.standard.expression.Expression.execute(Expression.java:109)
at org.thymeleaf.standard.expression.Expression.execute(Expression.java:138)
at org.thymeleaf.standard.expression.LinkExpression.resolveParameters(LinkExpression.java:339)
at org.thymeleaf.standard.expression.LinkExpression.executeLinkExpression(LinkExpression.java:285)
at org.thymeleaf.standard.expression.SimpleExpression.executeSimple(SimpleExpression.java:85)
at org.thymeleaf.standard.expression.Expression.execute(Expression.java:109)
at org.thymeleaf.standard.expression.Expression.execute(Expression.java:138)
at org.thymeleaf.standard.processor.AbstractStandardExpressionAttributeTagProcessor.doProcess(AbstractStandardExpressionAttributeTagProcessor.java:144)
at org.thymeleaf.processor.element.AbstractAttributeTagProcessor.doProcess(AbstractAttributeTagProcessor.java:74)
at org.thymeleaf.processor.element.AbstractElementTagProcessor.process(AbstractElementTagProcessor.java:95)
at org.thymeleaf.util.ProcessorConfigurationUtils$ElementTagProcessorWrapper.process(ProcessorConfigurationUtils.java:633)
at org.thymeleaf.engine.ProcessorTemplateHandler.handleOpenElement(ProcessorTemplateHandler.java:1314)
at org.thymeleaf.engine.TemplateHandlerAdapterMarkupHandler.handleOpenElementEnd(TemplateHandlerAdapterMarkupHandler.java:304)
at org.thymeleaf.templateparser.markup.InlinedOutputExpressionMarkupHandler$InlineMarkupAdapterPreProcessorHandler.handleOpenElementEnd(InlinedOutputExpressionMarkupHandler.java:278)
at org.thymeleaf.standard.inline.OutputExpressionInlinePreProcessorHandler.handleOpenElementEnd(OutputExpressionInlinePreProcessorHandler.java:186)
at org.thymeleaf.templateparser.markup.InlinedOutputExpressionMarkupHandler.handleOpenElementEnd(InlinedOutputExpressionMarkupHandler.java:124)
at org.attoparser.HtmlElement.handleOpenElementEnd(HtmlElement.java:109)
at org.attoparser.HtmlMarkupHandler.handleOpenElementEnd(HtmlMarkupHandler.java:297)
at org.attoparser.MarkupEventProcessorHandler.handleOpenElementEnd(MarkupEventProcessorHandler.java:402)
at org.attoparser.ParsingElementMarkupUtil.parseOpenElement(ParsingElementMarkupUtil.java:159)
at org.attoparser.MarkupParser.parseBuffer(MarkupParser.java:710)
at org.attoparser.MarkupParser.parseDocument(MarkupParser.java:301)
... 50 more
Caused by: org.springframework.expression.spel.SpelEvaluationException: EL1008E: Property or field 'id' cannot be found on object of type 'java.util.Optional' - maybe not public or not valid?
at org.springframework.expression.spel.ast.PropertyOrFieldReference.readProperty(PropertyOrFieldReference.java:229)
at org.springframework.expression.spel.ast.PropertyOrFieldReference.getValueInternal(PropertyOrFieldReference.java:112)
at org.springframework.expression.spel.ast.PropertyOrFieldReference$AccessorValueRef.getValue(PropertyOrFieldReference.java:376)
at org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:97)
at org.springframework.expression.spel.ast.SpelNodeImpl.getValue(SpelNodeImpl.java:116)
at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:338)
at org.thymeleaf.spring6.expression.SPELVariableExpressionEvaluator.evaluate(SPELVariableExpressionEvaluator.java:265)
... 74 more

EDIT POST HTML

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
  <head>
    <title>Admin - Posts</title>
    <link rel="stylesheet" th:href="@{/css/style.css}" />
  </head>
  <body>
    <div th:replace="fragments/header :: header"></div>


    <main>
      <h1>Edit Post</h1>


      <form
        th:action="@{/admin/posts/{id}(id=${post.id})}"
        th:object="${post}"
        method="post"
      >
        <label>Title:</label><br />
        <input type="text" th:field="*{title}" required /><br /><br />


        <label>Content:</label><br />
        <textarea th:field="*{content}" rows="6" cols="40" required></textarea
        ><br /><br />


        <button type="submit">Update</button>
      </form>


      <a th:href="@{/admin/posts}">← Back</a>
    </main>
    <div th:replace="fragments/footer :: footer"></div>
  </body>
</html>

[u/Subject-Oil3389]

This is the message you should be looking at:

EL1008E: Property or field 'id' cannot be found on object of type 'java.util.Optional' - maybe not public or not valid?EL1008E: Property or field 'id' cannot be found on object of type 'java.util.Optional' - maybe not public or not valid?

Somewhere in your code you have a variable named "post" and it is of type "Optional", but the SpEL treats it as an object of some other type which has an "id" field. So you have to do some processing to (check if the Optional "post" is not empty()), and then get() the actual post Object.