Hi @christophe17908
What is the make and model number of the PC or the motherboard if it is a custom build PC?
If the PC currently has WinXP installed it may be too old and is not compatible with Win11 so it won't be able to be updated.
Here's a [https://www.cnet.com/tech/computing/not-sure-if-your-pc-is-compatible-with-windows-11-heres-how-to-check/|link] that may help you to find out whether it can or cannot be updated.