This will add a console command that will automatically update: vendor/jenssegers/mongodb/src/Jenssegers/Mongodb/Connection.php and include the necessary functions/commands for beginTransaction(). This fixes Call to a member function beginTransaction() on null
Simply move MongoDBTransactionFix.php to app/Console/Commands. Create Commands folder if does not exist.
Run php artisan fix:transaction. To revert, run php artisan fix:transaction --rollback