Unable to update iPad mini 4 past iOS 15.8.4

The iPad mini4 is fundamentally does not support iPadOS 16 or later - as this model lacks the required system resources (CPU & RAM).

For information, as of 27 January 2025, here is a list of the highest version of iOS supported by the older models of iPad (for simplicity - “generations” are shortened to a number) that are restricted in their ability to be updated:

32-bit devices (obsolete)

iPad1 - iOS 5.1.1

iPad2, iPad3 and iPad mini1 - iOS 9.3.5 (WiFi Only models), iOS 9.3.6 (WiFi+Cellular)

iPad4 - iOS 10.3.3 (WiFi Only), iOS 10.3.4 (WiFi+Cellular)

64-bit devices

iPad Air1*, iPad mini2 and iPad mini3* - iOS 12.5.7

iPad Air2, iPad mini4 - iPadOS 15.8.3

iPad5, iPad Pro (9.7"/12.9" 1st generation)* - iPadOS 16.7.10

iPad6, iPad Pro (10.5"/12.9" 2nd generation) - iPadOS 17.7.4

(*) obsolete

Newer models are all able to be updated to the current version - iPadOS 18.3

• iPad Pro 13" (M4)
• iPad Pro 12.9" (3rd generation and later)
• iPad Pro 11" (1st generation and later + M4)
• iPad Air (3rd generation and later + M2)
• iPad (7th generation and later)
• iPad mini (5th generation and later + A17 Pro)

Usually the reason why a device is no longer supported past a certain iOS version is because the hardware cannot reliably run the new features of a new operating system.

For example optimisations for older or obsolete chips will be removed in order to maintain a fast and efficient operating system for more recent devices. But there may also be other reasons.

Nevertheless the Mini 4 has had a long run having first been released in 2015.