Laravel 5 TokenMismatchException on login - laravel

Question

I developed an application with laravel locally with homestead and now I try to get it running on a shared host. As soon as I hit the login button I get the exception: TokenMismatchException in VerifyCsrfToken.php line 53
I read that many people have problems with the TokenMismatchException but all of the proposed solutions didn't work for me. I deleted all files in the storage/framework/sessions folder (and the folder has 777 permissions). I deleted all cookies and since I use {!! Form:open !!} the hidden _token field exists (I also posted the source code).
My whole app expects the user to be logged in, so immediately after visiting the page I get redirected to the login form.
auth/login.blade.php
#extends('app')
#section('content')
<div class="container-fluid">
<div class="row">
<div class="col-md-8 col-md-offset-2">
<div class="panel panel-default">
<div class="panel-heading">Login</div>
<div class="panel-body">
{!! Form::open(array('url' => '/auth/login', 'class' => 'form-horizontal')) !!}
<div class="form-group">
<label class="col-md-4 control-label">E-Mail Address</label>
<div class="col-md-6">
{!! Form::email('email', null, ['class' => 'form-control']) !!}
</div>
</div>
<div class="form-group">
<label class="col-md-4 control-label">Password</label>
<div class="col-md-6">
{!! Form::password('password', ['class' => 'form-control']) !!}
</div>
</div>
<div class="form-group">
<div class="col-md-6 col-md-offset-4">
{!! Form::checkbox('remember', '1', false, ['id' => 'remember']) !!}
{!! Form::label('remember', 'Remember Me') !!}
</div>
</div>
<div class="form-group">
<div class="col-md-6 col-md-offset-4">
{!! Form::submit("Login", ['class' => 'btn btn-block btn-primary']) !!}
</div>
</div>
{!! Form::close() !!}
#if (count($errors) > 0)
<div class="alert alert-danger">
<strong>Whoops!</strong> There were some problems with your input.<br><br>
<ul>
#foreach ($errors->all() as $error)
<li>{{ $error }}</li>
#endforeach
</ul>
</div>
#endif
</div>
</div>
</div>
</div>
</div>
#endsection
This is how the source code looks like:
<input name="_token" type="hidden" value="HoSZ4shS8b1avwrkJZzGiUQCWRZL0VPtj3mfvJmI">
<div class="form-group">
<label class="col-md-4 control-label">E-Mail Address</label>
<div class="col-md-6">
<input class="form-control" name="email" type="email">
</div>
</div>
<div class="form-group">
<label class="col-md-4 control-label">Password</label>
<div class="col-md-6">
<input class="form-control" name="password" type="password" value="">
</div>
</div>
<div class="form-group">
<div class="col-md-6 col-md-offset-4">
<input id="remember" name="remember" type="checkbox" value="1">
<label for="remember">Remember Me</label>
</div>
</div>
<div class="form-group">
<div class="col-md-6 col-md-offset-4">
<input class="btn btn-block btn-primary" type="submit" value="Login">
</div>
</div>
</form>
Part of my routes.php
Route::get('auth/login', 'Auth\AuthController#getLogin');
Route::post('auth/login', 'Auth\AuthController#postLogin');
Route::get('auth/logout', 'Auth\AuthController#getLogout');
I'm not sure which code is necessary to see to be able to help me with this, please let me know if I need to post some more.
Thanks to everyone who cares about my question.

Answer 1

Is the URL in the <form> tag correct? Is the host name the same as the one where you're visiting the page?
I'll explain:
Imagine you're developing a site at http://www.mypage.com and while you're developing, you're visiting http://localhost.
If you visit http://localhost/auth/login and the form tag looks like this:
<form action="http://www.mypage.com/something">
You're going to get the TokenMismatchException when you submit a form.
Why? It's all about cookies.
When you visit a page at http://localhost, Laravel creates a session and saves the session ID to your browser in a cookie. Cookies are (generally) only accessible to pages from the same host, so if you visit http://localhost/page1 and http://localhost/page2, the server knows that those two visits are part of the same session because the cookie is accessible on both page visits.
If, on the other hand, you visit http://localhost/page1, then you visit http://www.mypage.com/page2, the server has no way of knowing that those two visits are part of the same session, because the cookie that was set when you visited page1 is not available when you visit page2 (because the host name is different).
So, that's what I think is happening:
you visit http://localhost/auth/login while you're developing.
Laravel sets up a CSRF token and adds it to the form on the page
Laravel also inserts the action for the form tag as http://www.mypage.com/auth/login (or whatever the default value is).
You click submit and the request is sent to http://www.mypage.com/auth/login (because that's what's in the form tag)
Laravel gets a token which does not match what it saved for your session at http://www.mypage.com (if a session even exists) because it doesn't have the session ID that it assigned to the session visiting http://localhost
The solution is to check your config & ensure that you're doing all the development via visits to a single hostname.

Answer 2

I somehow solved this now. I installed Laravel from scratch on the server and tried to copy as little as possible and make most changes manually. Don't know what lead to this Exception though.
Here is the thread that led me to the solution: https://laracasts.com/discuss/channels/code-review/request-session-token-not-equal-token/