Did you install with PHP 8.1?
The XC docs clearly states 7.4 or 8.0
https://developer.x-cart.com/getting_started/requirements
PHP (7.4 or 8.0)
So PHP 8.1.x, MySQL 8, env file with dev environment, debug set to 1, all other settings as needed.
First attempt to install clean copy failed with "SQLSTATE[HY000] [2002] No handler for this scheme" error. It took me some time to realize the db socket not being specified in .env file is the reason. So make sure all DB info in the .env file is properly added.
Then off to the next error - "Handling "XCart\Messenger\Message\SendMail" failed: Warning: Undefined array key "REQUEST_URI" - which is not something I could find in any settings file to adjust.
Changed the "debug" in .env file to false produces next error
"You cannot define a sequence item when in a mapping at line 11 (near "- 'CREATE TABLE xc_countries (code CHAR(2) NOT NULL, active_currency INT DEFAULT NULL, currency_id INT UNSIGNED DEFAULT NULL, lng_id INT DEFAULT NULL, id INT NOT NULL, code3 CHAR(3) NOT NULL, enabled TINYINT(1) NOT NULL, INDEX IDX_63D5E39A38248176 (currency_id), INDEX IDX_63D5E39AD7077436 (lng_id), INDEX enabled (enabled), INDEX active_currency (active_currency), PRIMARY KEY(code)) DEFAULT CHARACTER SET utf8mb4 COLLATE `utf8mb4_unicode_ci` ENGINE = InnoDB'")."
At this time I just gave up for the time being. Now this was a clean install attempt and I want to run an upgrade but I cannot imagine running this on a live store and failing like that. It will be disastrous.