Updating to iPadOS

The first generation iPad Air, iPad mini2 and mini3 can only be updated to iOS 12.5.5. With this version installed, you will have one of these three models.

Identify your iPad model - Apple Support

Apple ended major update support for these models of iPad in September 2019 - although they continued to receive “point” security updates until late last year. These devices cannot be updated to iPadOS 13 (or any later major versions of iPadOS) as the internal hardware does not meet the minimum technical requirements (CPU and RAM) for newer versions of iOS/iPadOS.

Some App developers have dropped support for iOS versions preceding iOS 13.x for technical reasons (often because APIs or software libraries upon which they rely have been updated in the new version of iPadOS, making their App incompatible with earlier versions). 

Whilst many App titles remain compatible with your iPad, if you want or need to access to Apps requiring more recent versions of iOS than your iPad is capable of support, you have no alternative other than to consider replacement of your iPad with a newer or current model that supports iPadOS15.x.

Sorry, I appreciate that this may not be what you were hoping to learn.

I hope this information provides helpful clarity as to your available options - and the fundamental limitations of your existing iPad.

An unit running 12.5.5 isn't capable of 13 or above and won't be a third generation iPad Air.

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The only iPad Air model which would be running 12.5.5 is the first generation one. Newer units went from 12.4.1 to 13.0.

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Check the model number in Settings>General>About

As has already been stated, if it is running 12.5.5, it is not a 3rd gen iPad Air.