diff --git a/frontend/contexts/AuthContext.tsx b/frontend/contexts/AuthContext.tsx
index 416226f..52f80fc 100644
--- a/frontend/contexts/AuthContext.tsx
+++ b/frontend/contexts/AuthContext.tsx
@@ -47,6 +47,28 @@ const AuthContext = createContext<AuthContextType | undefined>(undefined);
 export const AuthProvider: React.FC<{ children: ReactNode }> = ({ children }) => {
   const [user, setUser] = useState<User | null>(null);
 
+  const getErrorMessage = (errorKey: string): string => {
+    // Map backend error messages to Portuguese
+    const errorMap: { [key: string]: string } = {
+      "email already registered": "Este e-mail já está cadastrado.",
+      "invalid credentials": "E-mail ou senha incorretos.",
+      "user not found": "Usuário não encontrado.",
+      "crypto/bcrypt: hashedPassword is not the hash of the given password": "Senha incorreta.",
+      "password is too short": "A senha é muito curta.",
+      "cpf already registered": "CPF já cadastrado.",
+    };
+
+    // Check for partial matches or exact matches
+    if (errorMap[errorKey]) return errorMap[errorKey];
+
+    // Fallbacks
+    if (errorKey.includes('hashedPassword')) return "Senha incorreta.";
+    if (errorKey.includes('email')) return "Erro relacionado ao e-mail.";
+    if (errorKey.includes('password')) return "Erro relacionado à senha.";
+
+    return "Ocorreu um erro inesperado. Tente novamente.";
+  };
+
   const login = async (email: string, password?: string) => {
     // 1. Check for Demo/Mock users first
     const mockUser = MOCK_USERS.find(u => u.email === email);
@@ -65,8 +87,8 @@ export const AuthProvider: React.FC<{ children: ReactNode }> = ({ children }) =>
       });
 
       if (!response.ok) {
-        console.error('Login failed:', response.statusText);
-        return false;
+        const errorData = await response.json().catch(() => ({}));
+        throw new Error(getErrorMessage(errorData.error || 'Falha no login'));
       }
 
       const data = await response.json();
@@ -107,7 +129,9 @@ export const AuthProvider: React.FC<{ children: ReactNode }> = ({ children }) =>
 
       if (!response.ok) {
         const errorData = await response.json().catch(() => ({}));
-        throw new Error(errorData.error || 'Falha no cadastro');
+        const rawError = errorData.error || 'Falha no cadastro';
+        // Allow passing raw error if it's not in map, or map it
+        throw new Error(getErrorMessage(rawError));
       }
 
       return true;
diff --git a/frontend/pages/Login.tsx b/frontend/pages/Login.tsx
index 2ea83b3..0b30f1e 100644
--- a/frontend/pages/Login.tsx
+++ b/frontend/pages/Login.tsx
@@ -22,9 +22,16 @@ export const Login: React.FC<LoginProps> = ({ onNavigate }) => {
     setIsLoading(true);
     setError('');
 
-    const success = await login(email, password);
-    if (!success) {
-      setError('Usuário não encontrado. Tente um dos e-mails de demonstração.');
+    try {
+      const success = await login(email, password);
+      // If mock login returns true (it doesn't throw), we are good.
+      // If real login throws, we catch it below.
+      if (!success) {
+        // Fallback for mock if it returns false without throwing
+        setError('Credenciais inválidas, tente novamente ou tente um dos e-mails de demonstração.');
+      }
+    } catch (err: any) {
+      setError(err.message || 'Erro ao realizar login');
     }
     setIsLoading(false);
   };
diff --git a/frontend/pages/Register.tsx b/frontend/pages/Register.tsx
index eeb0c01..8aa004b 100644
--- a/frontend/pages/Register.tsx
+++ b/frontend/pages/Register.tsx
@@ -305,6 +305,12 @@ export const Register: React.FC<RegisterProps> = ({ onNavigate }) => {
                             </label>
                         </div>
 
+                        {error && !error.includes('termos') && !error.includes('senha') && !error.includes('coincidem') && (
+                            <div className="bg-red-50 border border-red-200 text-red-600 px-4 py-3 rounded-lg text-sm mb-4">
+                                {error}
+                            </div>
+                        )}
+
                         <Button type="submit" className="w-full" size="lg" isLoading={isLoading}>
                             {formData.wantsToAddInstitution ? 'Continuar para Universidade' : 'Criar Conta'}
                         </Button>