Erro no arquivo function.php

[luacarol]

Não sei o porque mas toda vez que vou tentar entrar com o login e senha na página do admin, o sistema dá esse erro. Já tentei de tudo, mas está difícil achar uma solução. Alguém pode me ajudar?

Slim Application Error
The application could not run because of the following error:

Details
Code: 8
Message: Undefined index: deslogin
File: C:\ecommerce\functions.php
Line: 5
Trace
#0 C:\ecommerce\functions.php(5): Slim\Slim::handleErrors(8, 'Undefined index...', 'C:\ecommerce\fu...', 5, Array)
#1 C:\ecommerce\index.php(43): post('deslogin')
#2 [internal function]: {closure}()
#3 C:\ecommerce\vendor\slim\slim\Slim\Router.php(200): call_user_func_array(Object(Closure), Array)
#4 C:\ecommerce\vendor\slim\slim\Slim\Slim.php(1210): Slim\Router->dispatch(Object(Slim\Route))
#5 C:\ecommerce\vendor\slim\slim\Slim\Middleware\Flash.php(86): Slim\Slim->call()
#6 C:\ecommerce\vendor\slim\slim\Slim\Middleware\MethodOverride.php(94): Slim\Middleware\Flash->call()
#7 C:\ecommerce\vendor\slim\slim\Slim\Middleware\PrettyExceptions.php(67): Slim\Middleware\MethodOverride->call()
#8 C:\ecommerce\vendor\slim\slim\Slim\Slim.php(1159): Slim\Middleware\PrettyExceptions->call()
#9 C:\ecommerce\index.php(122): Slim\Slim->run()
#10 {main}