If "Remember Me" is not ticked during login, Laravel logs the user out immediately

apache?

The problem I have in mind is stuff being output before the laravel headers.

This is caused by having some characters before the opening <?php in literally ANY class that gets run as part of the request cycle.

Only solution is to check all files that you have modified. And also make sure you haven't put ?> at the end of any file

This

"Header may not contain more than a single header, new line detected"

is what makes me think you are echoing data before the response somewhere.

Check if your browser is receiving the Laravel cookie.

Open the browser devtools and check the response from the server for the pages you are looking at. The very first characters recieved should be as per your blade master layout. Are they?

OKAY! Hold on, what!? The problem is now fixed. I don't even know what that did to fix it. So here is what I did. I re-ran the initial scaffolding of php artisan ui vue --auth. This then asked me yes or no on a bunch of files because I was replacing them. After saying yes to all of them the problem was fixed. Further investigation lead to this: on my home page I am running two vue graphs:

    <div class="col-md-4 mr-5 charts-container">
        <div class="col-md-12">
            <team-graph
                    :labels="[@foreach($users as $user)'{{$user->name}}',@endforeach]"
                    :active-leads="[@foreach($users as $user) {{$user->leads->whereIn('lead_status_id', [2,3])->count()}},@endforeach]"
                    :inactive-leads="[@foreach($users as $user) {{$user->leads->whereIn('lead_status_id', [1,4])->count()}},@endforeach]"
                    :dead-leads="[@foreach($users as $user) {{$user->leads->whereIn('lead_status_id', [5,7])->count()}},@endforeach]"
               ></team-graph>
        </div>
        <div class="col-md-12 mt-5">
             <revenue-graph url="/api/revenue"></revenue-graph>
        </div>
    </div>
    <div class="col-md-4">
        <h1 class="mb-4">Welcome back, {{Auth::user()->name}}</h1>
        <strong>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor.</strong>
        <p class="mt-4">Recent Updates</p>
        @for ($i = 0; $i <= 4; $i++)
                <div class="mb-4 mt-4 col-md-12">
                <div class="col-md-2">
                    <img src="https://picsum.photos/60/60?random={{$i}}" alt="..." class="rounded-circle">
                </div>
                <div class="col-md-9 mb-3">Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.</div>
                </div>
        @endfor
    </div>
</div>```

Since these were removed by the process I described above, my login now works. I have no idea how though still.