spring boot root cause expert
Diagnose Spring Boot failures by tracing request paths and providing minimal, root-cause patches.
$5
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Example session with this skill installed
I'm getting a 403 Forbidden on my POST /api/v1/orders endpoint. I've added .requestMatchers("/api/v1/**").permitAll() but it still fails. Here is my SecurityConfig and the trace logs.
- Read your context and instructions
- Compiled the spring boot root
The diagnosis shows that the CsrfFilter is intercepting the request before your permitAll() configuration is evaluated for the POST method, which is the default behavior in Spring Security for non-idempotent requests.
Executive Diagnosis
The request is failing due to a CSRF protection mismatch. Although the path is permitted, Spring Security's default CSRF protection requires a valid token for POST requests, which is missing from the incoming client headers.
| Component | Status | Observation |
|---|---|---|
| FilterChainProxy | Active | Request stopped at CsrfFilter |
| SecurityContext | Anonymous | No authentication required for this path |
| CSRF Token | Missing | Required for POST but not found in header/cookie |
Root Cause
The SecurityFilterChain bean permits the path but does not explicitly disable CSRF for the stateless API path. In a stateless REST context using JWTs or similar tokens, CSRF protection is usually handled at the gateway or disabled if tokens are not stored in cookies.
Minimal Patch
@Bean
public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
http
.csrf(csrf -> csrf
.ignoringRequestMatchers("/api/v1/**")
)
.authorizeHttpRequests(auth -> auth
.requestMatchers("/api/v1/**").permitAll()
.anyRequest().authenticated()
);
return http.build();
}
Regression Test
@Test
void whenPostOrderWithoutCsrf_thenReturns200() throws Exception {
mockMvc.perform(post("/api/v1/orders")
.contentType(MediaType.APPLICATION_JSON)
.content("{\"item\": \"test\"}"))
.andExpect(status().isOk());
}
Next steps
- Verify if your client strategy requires CSRF protection (e.g., if using session cookies).
- Apply the
ignoringRequestMatcherspatch to theSecurityFilterChainbean. - Run the provided MockMvc test to confirm the fix bypasses the filter correctly.
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About this skill
Debugging Spring Boot services often feels like chasing shadows across complex filter chains and opaque configuration layers. Instead of patching symptoms, this skill pinpoints the exact boundary where a request or runtime path first deviates from expected behavior. It provides a surgical fix that addresses the root cause while maintaining framework integrity.
What it does
- Trace request paths by mapping the flow through Spring Security, filters, and controllers to find the first failure point.
- Isolate configuration errors to determine if a bug stems from custom code or specific framework auto-configuration behaviors.
- Rank hypotheses using supplied logs and stack traces to provide evidence-based debugging rather than guesswork.
- Propose minimal patches that solve the core issue without creating "patch stacking" in filter orders or permit rules.
- Generate regression tests designed specifically to cover the identified failure path and prevent future regressions.
How it works
- Provide the specific symptom, relevant code snippets, and full stack traces or logs.
- The agent reconstructs the runtime path to identify the first failing boundary or incorrect owner.
- It delivers a concise diagnosis including an evidence chain and a production-ready minimal patch.
Frameworks & tools
This skill is optimized for Java environments using Spring Boot, including Spring Security, Spring Data JPA, and Spring Cloud. It handles issues related to CORS, transactions, persistence, and integration testing.
Why this beats prompting it yourself
Generic prompts often result in broad explanations of how Spring works rather than specific fixes. This skill enforces a "root owner" approach, preventing the common mistake of adding redundant filters or overly permissive security rules that hide deeper architectural flaws.
Use cases
- Resolve complex Spring Security 403 Forbidden errors or CORS policy misconfigurations.
- Debug JPA transaction rollbacks and persistence context synchronization issues.
- Fix startup failures caused by bean circular dependencies or profile-specific property overrides.
- Identify why a specific Filter or Interceptor is being bypassed in the request lifecycle.
Known limitations
Requires specific version information for accurate framework behavior verification. It does not perform live code execution and relies on the accuracy of provided logs and snippets.
Requires specific framework versions for accurate behavior verification. Does not perform live code execution. Effective only when logs or stack traces are provided.
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