The Windows 10 upgrade is here, and millions of people have already signed up — but would it be a mistake for you to get it for your PC?

The upgrade will apply to all users of Windows 7 and Windows 8.1, who will all get a free upgrade to Windows 10 on their tablets, laptops, and PCs — but there are some good reasons to completely avoid this upgrade, at least for now, according to a Newsweek report.

Windows users are probably seeing the “Get Windows 10 app” on the bottom right-hand corner of their monitors, which if clicked on would prompt you to reserve a free upgrade and enter your email address. If you haven’t reserved your spot yet, you may have to wait weeks or months after the general rollout. But that might be OK.

For one thing, it will be a lot more time consuming than you might think — the installation takes about an hour, so don’t do it in the middle of your workday. And that doesn’t count the time you might need to troubleshoot other software that stops working because of it.

Another thing is the reality of bugs on Day 1 rollouts. Whenever there is massive operating system upgrade, there are going to be a bugs that need to be patched, especially consider Windows’ reputation over the years.

Also, your system won’t necessarily be able to handle it even if it is technically compatible. There will be a bunch of additional requirements for other new features like Cortana, Continuum, and Windows Hello.

You might want to back up your files if you’re getting the upgrade, even though technically they should be safe. OS upgrades are big upheavals for a computer, and things can go wrong — you certainly don’t want to leave it to chance.

And then there’s the possibility that all your printers, hardware, and software will have trouble with the upgrade, requiring you to either re-install them, spend hours troubleshooting them, or just give up altogether and stop using them.

So it might be wise to give it a few months before upgrading and you can know what to expect.