500 Error after upgrading form 1.6.1.24 to 1.7.5.2

[merlinak]

Hello, I have tried to update from 1.6.1.24 to 1.7.5.2, but now when I try the admin page, I get 500 error.

In prod.log is this :

[2019-07-04 07:49:07] request.CRITICAL: Uncaught PHP Exception Symfony\Component\Debug\Exception\ClassNotFoundException: "Attempted to load class "Dispatcher" from the global namespace. Did you forget a "use" statement?" at /data/www/altena.sk/www.altena.sk/admin*********/index.php line 99 {"exception":"[object] (Symfony\\Component\\Debug\\Exception\\ClassNotFoundException(code: 0): Attempted to load class \"Dispatcher\" from the global namespace.\nDid you forget a \"use\" statement? at /data/www/altena.sk/www.altena.sk/admin*********/index.php:99)"} []

In index.php at line 98 a 99 is :
// Prepare and trigger LEGACY admin dispatcher
Dispatcher::getInstance()->dispatch();

 

When I start debug mode, it writes me this :

FatalThrowableError
Call to a member function getRequestUri() on null

in Dispatcher.php line 533

 

Dispatcher.php
line 533 : $this->getRequest()->getRequestUri(),

/**
* Sets request uri and if necessary $_GET['isolang'].
*/
protected function setRequestUri()
{
$shop = Context::getContext()->shop;
if (!Validate::isLoadedObject($shop)) {
$shop = null;
}

$this->request_uri = $this->buildRequestUri(
$this->getRequest()->getRequestUri(), // line 533
Language::isMultiLanguageActivated(),
$shop
);
}