0x80190190 appears when signing in, buying something, downloading a game, or launching a game that needs an online check, and the console cannot complete its request to Xbox Live. In Microsoft's Windows networking documentation the value maps to HTTP 400, Bad Request, which means the service rejected the request. Microsoft publishes no dedicated Xbox support article for this code, so the steps below are the standard network and account troubleshooting for that failure, in the order worth trying.
If the status page is green, the network test passes, and the error continues for one account while another signs in fine, the problem is with that account, so verify its credentials and payment details in a browser. If no account can sign in after clearing the MAC address and power cycling, a factory reset keeping games and apps is the last local step before contacting Xbox Support.
What does 0x80190190 mean? It means the console's request to an Xbox Live service was rejected. In practice that points to a service problem, a network problem, or an account state that needs attention, and the status page is the fastest way to tell which.
Does Microsoft have an official page for 0x80190190? No dedicated Xbox support article for this code was found. Microsoft documents the value only as an HTTP 400 mapping in its Windows networking documentation.
Will clearing the alternate MAC address delete anything? No. It clears a network setting only. Games, saves, and accounts are untouched, but the console restarts afterward.