diff --git a/src/main/java/com/eactive/apim/portal/common/exception/PortalErrorController.java b/src/main/java/com/eactive/apim/portal/common/exception/PortalErrorController.java
index 3bc19dc..86a2fe6 100644
--- a/src/main/java/com/eactive/apim/portal/common/exception/PortalErrorController.java
+++ b/src/main/java/com/eactive/apim/portal/common/exception/PortalErrorController.java
@@ -1,6 +1,8 @@
 package com.eactive.apim.portal.common.exception;
 
 import org.springframework.boot.web.servlet.error.ErrorController;
+import org.springframework.core.env.Environment;
+import org.springframework.core.env.Profiles;
 import org.springframework.http.HttpStatus;
 import org.springframework.stereotype.Controller;
 import org.springframework.web.bind.annotation.RequestMapping;
@@ -16,6 +18,11 @@ import javax.servlet.http.HttpServletRequest;
 @Controller
 public class PortalErrorController implements ErrorController {
 
+    private final Environment environment;
+
+    public PortalErrorController(Environment environment) {
+        this.environment = environment;
+    }
 
     @RequestMapping(value = "/error", method = {RequestMethod.POST, RequestMethod.GET})
     public ModelAndView handleError(HttpServletRequest request) {
@@ -27,10 +34,94 @@ public class PortalErrorController implements ErrorController {
             }
             ModelAndView modelAndView = new ModelAndView("error");
             modelAndView.addObject("status", status);
+
+            if (isProd()) {
+                // prod 환경에서는 내부 오류 정보를 노출하지 않고 이전과 동일한 일반 안내 메시지만 표시
+                modelAndView.addObject("errorTitle", "일시적인 장애로 서비스가 중단되었습니다.");
+                modelAndView.addObject("errorDescription", "서비스 이용에 불편을 드려 죄송합니다. 빠른 서비스를 제공할 수 있게 준비하겠습니다.");
+            } else {
+                modelAndView.addObject("errorTitle", resolveTitle(status));
+                modelAndView.addObject("errorDescription", resolveDescription(status));
+                modelAndView.addObject("errorMessage", resolveErrorMessage(request, status));
+            }
             return modelAndView;
         }
 
         return new ModelAndView("redirect:/");
     }
 
+    private boolean isProd() {
+        return environment.acceptsProfiles(Profiles.of("prod"));
+    }
+
+    private String resolveTitle(Object status) {
+        HttpStatus httpStatus = resolveHttpStatus(status);
+        if (httpStatus == null) {
+            return "서비스 처리 중 오류가 발생했습니다.";
+        }
+
+        if (httpStatus == HttpStatus.FORBIDDEN) {
+            return "접근이 거부되었습니다.";
+        }
+        if (httpStatus == HttpStatus.NOT_FOUND) {
+            return "요청하신 페이지를 찾을 수 없습니다.";
+        }
+        if (httpStatus.is4xxClientError()) {
+            return "요청을 처리할 수 없습니다.";
+        }
+        if (httpStatus.is5xxServerError()) {
+            return "서비스 처리 중 오류가 발생했습니다.";
+        }
+        return httpStatus.getReasonPhrase();
+    }
+
+    private String resolveDescription(Object status) {
+        HttpStatus httpStatus = resolveHttpStatus(status);
+        if (httpStatus == HttpStatus.FORBIDDEN) {
+            return "요청이 보안 검증을 통과하지 못했습니다.";
+        }
+        if (httpStatus == HttpStatus.NOT_FOUND) {
+            return "주소가 변경되었거나 삭제되었을 수 있습니다.";
+        }
+        if (httpStatus != null && httpStatus.is5xxServerError()) {
+            return "잠시 후 다시 시도해 주세요.";
+        }
+        return "요청 내용을 확인한 뒤 다시 시도해 주세요.";
+    }
+
+    private String resolveErrorMessage(HttpServletRequest request, Object status) {
+        Object requestUri = request.getAttribute(RequestDispatcher.ERROR_REQUEST_URI);
+        HttpStatus httpStatus = resolveHttpStatus(status);
+        StringBuilder message = new StringBuilder();
+
+        message.append("HTTP ").append(status);
+        if (httpStatus != null) {
+            message.append(" ").append(httpStatus.getReasonPhrase());
+        }
+
+        if (requestUri != null) {
+            message.append(" / 요청 경로: ").append(requestUri);
+        }
+
+        Object exceptionMessage = request.getAttribute(RequestDispatcher.ERROR_MESSAGE);
+        if (exceptionMessage != null && !exceptionMessage.toString().trim().isEmpty()) {
+            message.append(" / 원인: ").append(exceptionMessage);
+        } else if (httpStatus == HttpStatus.FORBIDDEN) {
+            message.append(" / 원인: 접근 권한 또는 CSRF 토큰을 확인하세요.");
+        }
+
+        return message.toString();
+    }
+
+    private HttpStatus resolveHttpStatus(Object status) {
+        if (status instanceof Integer) {
+            return HttpStatus.resolve((Integer) status);
+        }
+        try {
+            return HttpStatus.resolve(Integer.parseInt(status.toString()));
+        } catch (NumberFormatException e) {
+            return null;
+        }
+    }
+
 }
diff --git a/src/main/java/com/eactive/apim/portal/config/PortalConfigSecurity.java b/src/main/java/com/eactive/apim/portal/config/PortalConfigSecurity.java
index dbe1065..bade8b2 100644
--- a/src/main/java/com/eactive/apim/portal/config/PortalConfigSecurity.java
+++ b/src/main/java/com/eactive/apim/portal/config/PortalConfigSecurity.java
@@ -13,7 +13,7 @@ import org.springframework.security.config.annotation.web.configuration.EnableWe
 import org.springframework.security.config.http.SessionCreationPolicy;
 import org.springframework.security.web.SecurityFilterChain;
 import org.springframework.security.web.authentication.UsernamePasswordAuthenticationFilter;
-import org.springframework.security.web.csrf.CookieCsrfTokenRepository;
+import org.springframework.security.web.csrf.HttpSessionCsrfTokenRepository;
 import org.springframework.security.web.session.HttpSessionEventPublisher;
 import org.springframework.security.web.util.matcher.AntPathRequestMatcher;
 
@@ -79,6 +79,13 @@ public class PortalConfigSecurity {
     @Bean
     public SecurityFilterChain filterChain(HttpSecurity http) {
         try {
+            // CSRF 토큰을 쿠키(XSRF-TOKEN) 대신 HTTP 세션에 저장한다.
+            // 운영(prod/eapim/devportal)은 동일 호스트(IP:PORT)에 여러 서비스가 떠 있어
+            // 쿠키가 호스트 단위로 공유·과포화되면서 XSRF-TOKEN 쿠키가 누락 → 로그인 403이 발생했다.
+            // 기존 클라이언트(X-XSRF-TOKEN 헤더, _csrf 파라미터)와 호환되도록 헤더명을 고정한다.
+            HttpSessionCsrfTokenRepository csrfTokenRepository = new HttpSessionCsrfTokenRepository();
+            csrfTokenRepository.setHeaderName("X-XSRF-TOKEN");
+
             http
                 .authenticationManager(portalAuthenticationManager)
                 .formLogin(form -> form
@@ -92,9 +99,10 @@ public class PortalConfigSecurity {
                     .logoutRequestMatcher(new AntPathRequestMatcher("/actionLogout.do", "GET"))
                     .logoutSuccessHandler(logoutSuccessHandler))
                 .csrf(csrf -> csrf
-                    .csrfTokenRepository(CookieCsrfTokenRepository.withHttpOnlyFalse())
+                    .csrfTokenRepository(csrfTokenRepository)
                     .ignoringRequestMatchers(new AntPathRequestMatcher("/_proxy/**/*"))
                     .ignoringRequestMatchers(new AntPathRequestMatcher("/api/session/check-duplicate"))
+                    .ignoringRequestMatchers(new AntPathRequestMatcher("/internal/migration/**"))
                 )
                 // 중복로그인/유휴 만료는 DB 기반 SessionValidationFilter가 처리 (maximumSessions 미사용)
                 .sessionManagement(session -> session
diff --git a/src/main/resources/static/js/djb/inquiry-comments.js b/src/main/resources/static/js/djb/inquiry-comments.js
index 705e6c1..96c1370 100644
--- a/src/main/resources/static/js/djb/inquiry-comments.js
+++ b/src/main/resources/static/js/djb/inquiry-comments.js
@@ -14,8 +14,9 @@
   const counterEl = document.getElementById('djbCommentCharCounter');
 
   function getCsrfToken() {
-    const match = document.cookie.match(/(?:^|;\s*)XSRF-TOKEN=([^;]+)/);
-    return match ? decodeURIComponent(match[1]) : '';
+    // 세션 기반 CSRF: 쿠키 대신 <meta name="_csrf">에서 토큰을 읽는다.
+    const meta = document.querySelector('meta[name="_csrf"]');
+    return meta ? meta.getAttribute('content') : '';
   }
 
   function fetchJson(url, options) {
diff --git a/src/main/resources/templates/views/apps/statistics/apiStatistics.html b/src/main/resources/templates/views/apps/statistics/apiStatistics.html
index a1606ea..896f9cf 100644
--- a/src/main/resources/templates/views/apps/statistics/apiStatistics.html
+++ b/src/main/resources/templates/views/apps/statistics/apiStatistics.html
@@ -329,17 +329,10 @@
         return x.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
       }
 
-      // Get CSRF token from cookie
+      // 세션 기반 CSRF: 쿠키 대신 <meta name="_csrf">에서 토큰을 읽는다.
       function getCsrfToken() {
-        var name = 'XSRF-TOKEN=';
-        var cookies = document.cookie.split(';');
-        for (var i = 0; i < cookies.length; i++) {
-          var cookie = cookies[i].trim();
-          if (cookie.indexOf(name) === 0) {
-            return decodeURIComponent(cookie.substring(name.length));
-          }
-        }
-        return '';
+        var meta = document.querySelector('meta[name="_csrf"]');
+        return meta ? meta.getAttribute('content') : '';
       }
 
       // Validate date range (max 40 days)
diff --git a/src/main/resources/templates/views/error.html b/src/main/resources/templates/views/error.html
index c1d8f53..5a7d0bd 100644
--- a/src/main/resources/templates/views/error.html
+++ b/src/main/resources/templates/views/error.html
@@ -210,12 +210,13 @@
         </div>
 
         <!-- Error Title -->
-        <h1 class="error-title">일시적인 장애로 서비스가 중단되었습니다.</h1>
+        <h1 class="error-title" th:text="${errorTitle ?: '서비스 처리 중 오류가 발생했습니다.'}">
+            서비스 처리 중 오류가 발생했습니다.
+        </h1>
 
         <!-- Error Description -->
-        <p class="error-description">
-            서비스 이용에 불편을 드려 죄송합니다.<br>
-            빠른 서비스를 제공할 수 있게 준비하겠습니다.
+        <p class="error-description" th:text="${errorDescription ?: '잠시 후 다시 시도해 주세요.'}">
+            잠시 후 다시 시도해 주세요.
         </p>
 
         <!-- Error Message (서버에서 전달된 에러 메시지가 있을 경우 표시) -->
diff --git a/src/main/resources/templates/views/fragment/djbank/head.html b/src/main/resources/templates/views/fragment/djbank/head.html
index 7094f9e..bf91cc8 100644
--- a/src/main/resources/templates/views/fragment/djbank/head.html
+++ b/src/main/resources/templates/views/fragment/djbank/head.html
@@ -6,6 +6,10 @@
 
     <meta content="https://www.eactive.co.kr/" property="og:url"/>
     <meta charset="UTF-8"/>
+
+    <!-- CSRF 토큰 (세션 기반). 정적 JS/AJAX에서 토큰·헤더명을 읽어 사용한다. -->
+    <meta name="_csrf" th:content="${_csrf != null ? _csrf.token : ''}"/>
+    <meta name="_csrf_header" th:content="${_csrf != null ? _csrf.headerName : 'X-XSRF-TOKEN'}"/>
     <meta content="max-age=0, public" http-equiv="Cache-Control"/>
     <meta content="index, follow" name="robots"/>
     <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0, user-scalable=no">
diff --git a/src/main/resources/templates/views/fragment/djbank/header_container.html b/src/main/resources/templates/views/fragment/djbank/header_container.html
index 54ee8ce..c5709ec 100644
--- a/src/main/resources/templates/views/fragment/djbank/header_container.html
+++ b/src/main/resources/templates/views/fragment/djbank/header_container.html
@@ -278,8 +278,15 @@
       }
 
       function csrfHeaders() {
-        var token = getCookie('XSRF-TOKEN');
-        return token ? { 'X-XSRF-TOKEN': token } : {};
+        // 세션 기반 CSRF: 쿠키 대신 <meta>에서 토큰·헤더명을 읽는다.
+        var tokenMeta = document.querySelector('meta[name="_csrf"]');
+        var headerMeta = document.querySelector('meta[name="_csrf_header"]');
+        var headers = {};
+        if (tokenMeta && tokenMeta.content) {
+          var headerName = (headerMeta && headerMeta.content) ? headerMeta.content : 'X-XSRF-TOKEN';
+          headers[headerName] = tokenMeta.content;
+        }
+        return headers;
       }
 
       function formatTime(sec) {