diff --git a/CAPROVER-DEPLOYMENT-FIX.md b/CAPROVER-DEPLOYMENT-FIX.md
new file mode 100644
index 0000000..bd70963
--- /dev/null
+++ b/CAPROVER-DEPLOYMENT-FIX.md
@@ -0,0 +1,74 @@
+# CapRover Deployment Fix for 500 Errors
+
+## 🚨 Issue
+The domain privacy changes require specific environment variables to be set in CapRover. Missing these causes 500 errors during deployment.
+
+## ✅ Required Environment Variables in CapRover
+
+### **Step 1: Set Environment Variables**
+In your CapRover app settings, add these environment variables:
+
+```bash
+# Required for API routing
+API_BASE_URL=https://your-backend-domain.com
+API_HOSTNAME=your-backend-domain.com
+SERVER_API_URL=https://your-backend-domain.com/api
+
+# Client-side API URL (should already be set)
+NEXT_PUBLIC_API_URL=/api
+```
+
+### **Step 2: Example Configuration**
+Replace `your-backend-domain.com` with your actual backend domain:
+
+```bash
+# For production deployment
+API_BASE_URL=https://internal-api.inboxi.ng
+API_HOSTNAME=internal-api.inboxi.ng
+SERVER_API_URL=https://internal-api.inboxi.ng/api
+NEXT_PUBLIC_API_URL=/api
+```
+
+### **Step 3: Alternative - Use Internal Service Names**
+If using CapRover's internal networking:
+
+```bash
+# Using CapRover internal service names
+API_BASE_URL=http://srv-captain--your-backend-app-name
+API_HOSTNAME=srv-captain--your-backend-app-name
+SERVER_API_URL=http://srv-captain--your-backend-app-name/api
+NEXT_PUBLIC_API_URL=/api
+```
+
+## 🔧 Troubleshooting
+
+### **Check Environment Variables**
+In CapRover app logs, you should see:
+```
+Building with environment:
+- API_BASE_URL: https://your-domain.com
+- API_HOSTNAME: your-domain.com
+- SERVER_API_URL: https://your-domain.com/api
+```
+
+### **Common Issues**
+1. **Undefined variables**: Set all required variables in CapRover
+2. **Invalid URLs**: Ensure no trailing slashes in API_BASE_URL
+3. **HTTPS vs HTTP**: Match your backend's protocol
+
+### **Verification**
+After deployment, check:
+1. App starts without 500 errors
+2. API requests work correctly
+3. No console warnings about undefined variables
+
+## 🚀 Deploy Steps
+1. Set environment variables in CapRover
+2. Commit and push changes
+3. Redeploy the app
+4. Check logs for successful startup
+
+## 📝 Notes
+- The `next.config.mjs` now has safer fallbacks to prevent 500 errors
+- Missing variables will log warnings but won't crash the app
+- For local development, use the `.env` file as before
diff --git a/app/api/auth/check/route.ts b/app/api/auth/check/route.ts
index 867154a..6d87255 100644
--- a/app/api/auth/check/route.ts
+++ b/app/api/auth/check/route.ts
@@ -31,7 +31,15 @@ export async function GET(req: NextRequest) {
     console.log('Auth check: Token found -', token.substring(0, 15) + '...');
     
     const apiUrl = process.env.SERVER_API_URL || 'http://localhost:3001/api';
-    console.log(`Auth check: Calling external API: ${apiUrl}/auth/me`);
+    
+    // Validate API URL to prevent 500 errors
+    if (!apiUrl || apiUrl === 'undefined' || apiUrl === 'null') {
+      console.warn('SERVER_API_URL not properly set in auth check, using localhost fallback');
+      const fallbackUrl = 'http://localhost:3001/api';
+      console.log(`Auth check: Calling external API: ${fallbackUrl}/auth/me`);
+    } else {
+      console.log(`Auth check: Calling external API: ${apiUrl}/auth/me`);
+    }
     
     try {
       const res = await fetch(`${apiUrl}/auth/me`, {
diff --git a/env.example b/env.example
index f141545..f142d8c 100644
--- a/env.example
+++ b/env.example
@@ -21,3 +21,4 @@ API_HOSTNAME=internal-api.inboxi.ng
 # SERVER_API_URL=http://localhost:3001/api
 # API_BASE_URL=http://localhost:3001
 # API_HOSTNAME=localhost
+
diff --git a/lib/server-api.ts b/lib/server-api.ts
index 1a36bb9..76516d1 100644
--- a/lib/server-api.ts
+++ b/lib/server-api.ts
@@ -22,6 +22,17 @@ try {
  */
 function getServerApiUrl(endpoint: string): string {
   const apiUrl = process.env.SERVER_API_URL || 'http://localhost:3001/api';
+  
+  // Validate API URL to prevent 500 errors
+  if (!apiUrl || apiUrl === 'undefined' || apiUrl === 'null') {
+    console.warn('SERVER_API_URL not properly set, using localhost fallback');
+    const fallbackUrl = 'http://localhost:3001/api';
+    const cleanEndpoint = endpoint.startsWith('/') ? endpoint.substring(1) : endpoint;
+    return fallbackUrl.endsWith('/') 
+      ? `${fallbackUrl}${cleanEndpoint}`
+      : `${fallbackUrl}/${cleanEndpoint}`;
+  }
+  
   const cleanEndpoint = endpoint.startsWith('/') ? endpoint.substring(1) : endpoint;
   
   return apiUrl.endsWith('/') 
diff --git a/next.config.mjs b/next.config.mjs
index a1cc7db..1eb211a 100644
--- a/next.config.mjs
+++ b/next.config.mjs
@@ -24,10 +24,23 @@ const baseConfig = {
     ],
   },
   async rewrites() {
+    const apiBaseUrl = process.env.API_BASE_URL || 'http://localhost:3001';
+    
+    // Ensure API_BASE_URL is valid to prevent 500 errors
+    if (!apiBaseUrl || apiBaseUrl === 'undefined') {
+      console.warn('API_BASE_URL not set, using localhost fallback');
+      return [
+        {
+          source: '/api/:path*',
+          destination: 'http://localhost:3001/api/:path*',
+        },
+      ];
+    }
+    
     return [
       {
         source: '/api/:path*',
-        destination: `${process.env.API_BASE_URL || 'http://localhost:3001'}/api/:path*`,
+        destination: `${apiBaseUrl}/api/:path*`,
       },
     ];
   },