My ipadOS is at 15.8.3 and i need update to higher

With iPadOS 15.8.3 installed, you presumably have either an iPad Air2 or iPad mini4 - neither of which support iPadOS 16.x or later.

If you need to use Apps that require a higher version of iPadOS than your iPad is capable of support, you have no alternative other than to replace your existing iPad with a much newer or current model iPad.

For information, 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" first generation) - iPadOS 16.7.10

(*) obsolete

Newer models are all able to be updated to the current version - iPadOS 17.6.1

• iPad Pro 13" (M4)
• iPad Pro 12.9" (2nd generation and later)
• iPad Pro 11" (1st generation and later + M4)
• iPad Pro 10.5"
• iPad Air (3rd generation and later + M2)
• iPad (6th generation and later)
• iPad mini (5th generation and later)

milica101 wrote:

My iPadOS is at 15.8.3 but I need to have it at 16.4 to be able to use an education app (i-Ready) my son needs. How do I update my iPad? When I go to General-Software Updates, it says my iPad is up to date already. Is there a way to install newer OS?

thx

No, your ipad is at the end of the line for ios updates.

You will need to upgrade to a newer ipad to get the latest ios.