"This page has expired due to inactivity" - Two php artisan serve instances running

Within seconds of accessing a test application created with Livewire, I started getting a “this page has expired due to inactivity” message.

After some troubleshooting, I realized that this behaviour was only occurring when I was running “php artisan serve” with two different test projects on my MacBook, from localhost at 8000 and 8001.

By shutting down the other, the rapid expiration behaviour stopped. I didn’t find this explanation elsewhere, so I decided to post here in case others find themselves in this scenario and end up wasting time debugging.