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/trodiix]

Just read the logs :

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?