Connectify Hotspot does not detect a Wi-Fi Adapter

To create a Wi-Fi hotspot or a Wi-Fi repeater, your computer needs a Wi-Fi adapter. If Connectify Hotspot can't find one when you click Start hotspot, it shows this error at the top of the window:

A Wi-Fi hotspot or Wi-Fi repeater needs a Wi-Fi adapter that supports AP mode. Please enable your Wi-Fi adapter or add a USB Wi-Fi adapter. Turn off Airplane mode if it's on.

The error shown when Connectify Hotspot finds no Wi-Fi adapter, with Launch Help and Dismiss

Usually you do have a Wi-Fi adapter, but it is disabled or switched off. Here is a checklist you should go through:

Do you have a Wi-Fi adapter, and is it enabled?

In Connectify Hotspot, go to Help and account, and next to Network connections, click Open. This opens Windows' list of network adapters.
Look for your Wi-Fi adapter and make sure it is enabled. If it's disabled, right-click it and choose Enable.

Help and account: Get help, with Network connections and its Open button

If you do not have a Wi-Fi adapter, you will need one to create a Wi-Fi hotspot. There are many USB Wi-Fi adapters available that you can use with Connectify Hotspot. Without Wi-Fi, you can still share your internet over Ethernet with Wired router (Hotspot PRO or MAX).

Is the Wi-Fi adapter connected and switched on?

If you have a USB Wi-Fi adapter, check that it is fully inserted into your computer.
Many laptops have a switch that turns the Wi-Fi adapter on and off. Sometimes this is a physical switch on the side of the computer. Make sure it's in the on position.
Check for a keyboard shortcut such as Fn+F8 (the key usually has a small Wi-Fi or airplane symbol on it). Make sure the shortcut hasn't turned your adapter off.
Make sure Airplane mode is off. Press Windows+A to open quick settings and check the Airplane mode button.
Your adapter could be disabled by a BIOS setting if your computer detects Ethernet is in use while connected over Wi-Fi. Look for an option along the lines of 'Auto LAN/WAN switching' in the BIOS, and turn it off.

Is your Wi-Fi adapter used by other software?

Connection management software, such as a 3G or 4G dialer, may turn off your Wi-Fi adapter when you are connected to another network.
If your Wi-Fi adapter is part of a network bridge, Connectify Hotspot can't use it. Removing the bridge will fix the issue.

Connectify Hotspot found my Wi-Fi adapter, but it still doesn't work

If the error says "Your Wi-Fi adapter does not support AP mode", your adapter's driver can't host a hotspot. See Your Wi-Fi adapter does not support AP mode.

In either case, make sure you have the latest drivers for your Wi-Fi adapter installed. Learn how to update them here: How to update your wireless (Wi-Fi) driver.