confirm to go in order as the fixes start with easiest and progressively get more involved.
verify you are signed in to the same Apple Account.
On your Mac, check fromApplemenu >System tweaks.

iPad with Apple Pencil.Alvaro Reyes / Unsplash
Confirm your Apple Account from theSettingsapp on your iPad.
Double-check that your gadget is supported.Our article about Sidecarexplains which devices are supported to use this feature.
ensure your iPad andMac are up to date.
CheckSystem tweaks>General>Software Updateon your Mac andSettings>General>Software Updateon your iPad.
Check to check that your iPad is unlocked.
If your iPad is locked, it’s possible for you to’t use Sidecar.
Check Handoff is enabled.
Handoff is a feature which allows Mac and iOS devices to share data wirelessly.
Check your iPad Bluetooth configs.
There could be a Bluetooth communication issue between the devices.
Tryturning Bluetooth off and back on again on your Macand iPad.
Keep your devices close together.
Try restarting both devices.
Try plugging your iPad into the Mac.
Use a USB cable to plug your iPad into your Mac to solve any wireless connection issues.
Check your iPad is a trusted unit fromtwo-factor authentication tweaks.
confirm your Mac isn’tsharing its Wi-Fi connection.
The same goes for youriPad sharing a cellular connection.
Clear a black screen.
FAQ
Not every iPad supports Sidecar.
Apple has alist of compatible deviceson its support site.
Along with the iPad requirements, you also need the right Mac.