* UEFI is not supported, you need to enable "legacy boot" in BIOS before installing Qubes OS
* Some icons in the Qubes Manager application might not be drawn correctly when using the Xfce4 environment in Dom0. If this bothers you, please use the KDE environment instead.
* If your GPU is not correctly supported by the Dom0 kernel (e.g. the 3D desktop effects do not run smoothly) then you might experience "heaviness" with Windows 7-based AppVMs. In that case, please solve the problem with your GPU support in Dom0 in the first place (by using a different kernel), or install Qubes OS on a different system.
* For other known issues take a look at [our tickets](https://github.com/QubesOS/qubes-issues/issues?q=is%3Aopen+is%3Aissue+milestone%3A%22Release+3%22+label%3Abug)
It is advised to install updates just after system installation to apply bug fixes for (some of) the above problems.
The easiest and safest way to upgrade to Qubes R3.0 is to install it from scratch and use [qubes backup and restore tools](/doc/BackupRestore/) for migrating of all of the user VMs.
Users of Qubes R2 can upgrade using [experimental procedure](/doc/UpgradeToR3.0/).