diff --git a/src/app/admin/courses/[courseId]/page.tsx b/src/app/admin/courses/[courseId]/page.tsx
index a49474b..977eb50 100644
--- a/src/app/admin/courses/[courseId]/page.tsx
+++ b/src/app/admin/courses/[courseId]/page.tsx
@@ -50,13 +50,21 @@ export default async function CourseDetailPage({ params }: Props) {
 
   if (!course) notFound();
 
+  // Prisma 7 returns proxy objects for relations/aggregates that RSC cannot serialize.
+  // Convert to plain JS before passing to Client Components.
+  const plain = JSON.parse(JSON.stringify({ course, allStudents, categories })) as {
+    course: typeof course;
+    allStudents: typeof allStudents;
+    categories: typeof categories;
+  };
+
   return (
     <div className="p-8 max-w-4xl">
       {/* Breadcrumb */}
       <nav className="text-xs mb-6 uppercase tracking-widest" style={{ color: "var(--muted-foreground)" }}>
         <Link href="/admin/courses" className="hover:underline">Курсы</Link>
         <span className="mx-2">/</span>
-        <span style={{ color: "var(--foreground)" }}>{course.title}</span>
+        <span style={{ color: "var(--foreground)" }}>{plain.course.title}</span>
       </nav>
 
       {/* Course metadata */}
@@ -64,7 +72,7 @@ export default async function CourseDetailPage({ params }: Props) {
         <p className="text-xs font-bold uppercase tracking-widest mb-5" style={{ color: "var(--muted-foreground)" }}>
           Основная информация
         </p>
-        <CourseEditForm course={course} categories={categories} />
+        <CourseEditForm course={plain.course} categories={plain.categories} />
       </section>
 
       {/* Modules */}
@@ -74,19 +82,19 @@ export default async function CourseDetailPage({ params }: Props) {
             Модули
           </p>
           <span className="text-xs" style={{ color: "var(--muted-foreground)" }}>
-            {course.modules.length} модулей
+            {plain.course.modules.length} модулей
           </span>
         </div>
-        <SortableModules courseId={courseId} modules={course.modules} />
+        <SortableModules courseId={courseId} modules={plain.course.modules} />
       </section>
 
       {/* Course tree overview */}
-      {course.modules.length > 0 && (
+      {plain.course.modules.length > 0 && (
         <section className="card-aubade p-6 mb-6">
           <p className="text-xs font-bold uppercase tracking-widest mb-5" style={{ color: "var(--muted-foreground)" }}>
             Структура курса
           </p>
-          <CourseTree courseId={courseId} modules={course.modules} />
+          <CourseTree courseId={courseId} modules={plain.course.modules} />
         </section>
       )}
 
@@ -97,9 +105,9 @@ export default async function CourseDetailPage({ params }: Props) {
         </p>
         <EnrollmentManager
           courseId={courseId}
-          allStudents={allStudents}
-          enrollments={course.enrollments}
-          accessLogs={course.accessLogs}
+          allStudents={plain.allStudents}
+          enrollments={plain.course.enrollments}
+          accessLogs={plain.course.accessLogs}
         />
       </section>
     </div>