Error updating iPad to iOS 12.4
When I go to update my iPad to IOS 12.4 it states an error occurred and will not allow the update to install.
Assuming you have a device which is capable of being updated to iOS 12.4, if you can't update over the air, do the update using your computer and iTunes.
This link will tell you how: Update your iPhone, iPad, or iPod touch - Apple Support
Follow the section about Updating your device using iTunes.