Can't redeem code for 1-month Xbox Game Pass Ultimate trial

If you redeem the 3 months of Game Pass Ultimate is the one that will count, you wont have 3 months plus 14 days, but only the 3 months. This happens always when you have activated a trial and you put a non trial code (1 month and above)

The 14 day codes are trials and will only work with new subscribers to Game Pass, which is why there's an error. You would need a code that is not a trial code (anything 1 month or above) or purchase Game Pass (or Ultimate) directly from Xbox.

I haven't had ultimate but I had normal game pass for pc before

That would be why you can't redeem it then...from the FAQs in the link I posted before:

"If you were previously subscribed or currently subscribed to Xbox Game Pass for PC, or an Xbox Game Pass Ultimate subscription, you will not be able to redeem the two month trial for Xbox Game Pass Ultimate!"

Did he gift you ultimate game pass or 1 year of gold? Since there is a 1:1 conversion ratio for a normal gold or game pass to Ultimate game pass. For example if you were to redeem a 3 month game pass code while you have ultimate it would convert to a little
over a month in ultimate.

No. Redeem your Gold first then redeem your Ultimate (like back to back within a few minutes of each other). What will happen is, the Ultimate will upgrade your Gold to Ultimate and add on the remaining 6 months which will give you 12 months of
Ultimate.

Thank you for the prompt response. I am trying to take advantage of black friday and able to get ultimate pass for 1 year, so gold for 1 year and ultimate pass for 1 year. How does this stacking combination work?

on side note, upon purchasing series x, i got 30 days of trial ultimate game pass code, can i stack it on top of yearly ultimate pass?