error when starting section with a microsoft account and fixing it with the notepad tutorial does not work

In December, I bought minecraft almost for Christmas, but as we know, the mojang accounts are changing for microsft accounts and every time I want to enter a server I get the message: error at login Authentication is disabled for maintenance, but that's not my case what happens that the mojang have found the solution to follow several steps, completing them does not work for me instead of letting me enter the server that I want to enter I get the message: Failed to login: null. every now and then I think the problem comes from the fact that I have used non-premium minecraft before, besides that minecraft reamls doesn't work too and I get an error, help me, what can I do?