diff --git a/server/storage.ts b/server/storage.ts
index 98a46ee..8aaa8a3 100644
--- a/server/storage.ts
+++ b/server/storage.ts
@@ -56,7 +56,7 @@ import {
   type InsertCcnlSetting,
 } from "@shared/schema";
 import { db } from "./db";
-import { eq, and, gte, lte, desc } from "drizzle-orm";
+import { eq, and, gte, lte, desc, or } from "drizzle-orm";
 
 export interface IStorage {
   // User operations (Replit Auth required)
@@ -163,22 +163,39 @@ export class DatabaseStorage implements IStorage {
   }
 
   async upsertUser(userData: UpsertUser): Promise<User> {
-    // Use onConflictDoUpdate to handle both insert and update cases
-    // This handles conflicts on both id (primary key) and email (unique constraint)
-    const [user] = await db
-      .insert(users)
-      .values(userData)
-      .onConflictDoUpdate({
-        target: users.id,
-        set: {
-          email: userData.email,
-          name: userData.name,
-          role: userData.role,
+    // Handle conflicts on both id (primary key) and email (unique constraint)
+    // Check if user exists by id or email first
+    const existingUser = await db
+      .select()
+      .from(users)
+      .where(
+        userData.id 
+          ? or(eq(users.id, userData.id), eq(users.email, userData.email || ''))
+          : eq(users.email, userData.email || '')
+      )
+      .limit(1);
+
+    if (existingUser.length > 0) {
+      // Update existing user - NEVER change the ID (it's a primary key)
+      const [updated] = await db
+        .update(users)
+        .set({
+          ...(userData.email && { email: userData.email }),
+          ...(userData.name && { name: userData.name }),
+          ...(userData.role && { role: userData.role }),
           updatedAt: new Date(),
-        },
-      })
-      .returning();
-    return user;
+        })
+        .where(eq(users.id, existingUser[0].id))
+        .returning();
+      return updated;
+    } else {
+      // Insert new user
+      const [user] = await db
+        .insert(users)
+        .values(userData)
+        .returning();
+      return user;
+    }
   }
 
   async getAllUsers(): Promise<User[]> {