Filament v4 migration – Livewire SupportValidation error and login redirect not working

I am migrating a project and found an issue I can’t resolve.
Here are the details:

Versions after migration
Filament: v4.0 (from v3.2.117)
PHP: 8.3 (from 8.2)
Laravel: 12.26.3 (from 11.44.0)
Livewire: 3.6.4 (from 3.5.6)

Problem
When loading the login route, I get the following error:

local.ERROR: IlluminateSupportViewErrorBag::put(): 
Argument #2 ($bag) must be of type IlluminateContractsSupportMessageBag, null given, 
called in /vendor/livewire/livewire/src/Features/SupportValidation/SupportValidation.php on line 21

Trace points to SupportValidation->render() and ViewErrorBag->put() receiving null instead of a MessageBag.

Temporary workaround
To bypass this, I temporarily patched SupportValidation and SupportTesting in the vendor/ folder so that a new MessageBag instance is created when getErrorBag() is null. Example (simplified):

if (! $bag instanceof MessageBag) {
    $bag = new MessageBag((array) $bag);
    if (method_exists($this->component, 'setErrorBag')) {
        $this->component->setErrorBag($bag);
    }
}

**With this hack:

The login page renders correctly.

Authentication works (confirmed via browser dev tools and Laravel logs).

But the redirect after login does not happen** — the user stays on the login page even though authentication is successful.

What I tried:

  • Verified that the user is authenticated (Auth::check() returns true).

  • Logs confirm login success (tail -f storage/logs/laravel.log).

  • Without patching the vendor files, the login page never renders (due to the null MessageBag error).

  • With patching, page renders but redirect is broken.

Questions

1 – Is this a known issue with Filament v4 + Livewire 3.6.x during login?

2 – Should I be initializing the MessageBag in a different way rather than patching vendor code?

3 – Why would the redirect fail even though authentication succeeds?

Unfortunately, my project is private, but I can try to create a minimal reproduction repo if needed.

Any help or guidance would be appreciated.