iPadOS 26.4 introduced a new bug that occasionally causes the onscreen numpad not to pop up on iPad. This has now been fixed in the 26.4.1 patch, however to install it, entering your passcode is needed. Luckily there is a solution:
How to Make the Numpad Visible
As seen here, the iPad is asking for a passcode, but there is no keyboard or numpad to input it. There is however some kind of grey bar on the bottom. Using 2 fingers to pinch this will bring up a small numpad, allowing the passcode to be entered.
Here’s a video to demonstrate:
Update to iPadOS 26.4.1 to Fix the Bug For Good
Even though we can make the numpad appear now, the bug will appear again occasionally until the 26.4.1 patch is installed, which fixes the problem.
Update
Apparently the bug can still occur in the 26.4.1 patch, though the same method works as a temporary solution. Still waiting for a fix from Apple…
