'This app can't run on your PC' and programs that will not install

These messages are usually about compatibility: the program was not made for your version of Windows, or something is stopping it from installing. Here is a safe way to work through it.

What the message usually means

• This app can't run on your PC: the program was built for a different kind of PC or an older Windows, such as a 32-bit program on a 64-bit PC, or a program for a different processor type.
• Windows protected your PC: SmartScreen does not recognise the program. This is a warning, not an error. If you are not certain the program is genuine, do not go on.
• Installation failed: there may be no space, the installer is damaged, or you do not have permission.

Easy things to try

1. Download the installer again from the maker's own website. Do not use download sites or links from adverts.
2. Check you have enough free space on the C: drive. Aim for several gigabytes spare.
3. Restart, then try again before you open anything else.
4. Right-click the installer and choose Run as administrator. You may need an administrator password.

Try compatibility mode

1. Right-click the program or installer and choose Properties.
2. Open the Compatibility tab, then click Run compatibility troubleshooter.
3. Choose Try recommended settings and test it.

Windows in S mode

Settings, then System, then Activation will say if you are in S mode. This only lets you install apps from the Microsoft Store. You can switch out of S mode for free in the Store, but it is a one-way change and cannot be undone, so only do it if you need to.

A very old program may no longer be supported. Look for a newer version from the maker.

Never do this

Do not turn off Windows Security, or follow advice telling you to ignore warnings.

When to get more help

Get in touch if the same error appears for a program you need for work, if you are not sure where the installer came from, or if you were told to install something by a caller or a pop-up. We can check it for you.