Urgent `eloquent orm` problem: Laravel 10 `Method not found` error after migration, totally stuck!

just upgraded my Laravel app to version 10, thought it would be smooth sailing. now, i'm getting this super frustrating `Method not found` error whenever i try to use some standard `eloquent orm` methods in my models, like `firstOrCreate` or even `updateOrCreate` it's literally stopping me dead in my tracks. i've been at this for hours and can't figure out if it's a namespace thing, a config issue, or some dependency clash. here's the error i keep seeing:

Illuminate\Database\Eloquent\Builder::firstOrCreate does not exist.

really need an expert to chime in with a quick fix, this is urgent. waiting for an expert reply.