ipad mini wont update from ios 9.3.5???

The iPad mini1 can only be updated to iOS 9.3.5 (WiFi Only models) or iOS 9.3.6 (WiFi & Cellular models).

Apple ended update support for iPad mini1 in September 2016. Your iPad cannot be updated to iOS 10 or later major versions of iOS as the internal hardware does not meet the minimum technical requirements for new versions of iOS/iPadOS. This limitation cannot be bypassed; iPad2 is a 32-bit architecture device, whilst all recent versions of iOS/iPadOS are designed for 64-bit hardware platforms. iPad mini1 is obsolete.

Compatible Apps for your iPad are increasingly difficult to find - as third-party developers are increasingly dropping support for older versions of iOS preceding iOS11/12/13. As older versions of Apps are removed from the Apple App Store, you’ll not be able to (re)download or install them - which may severely limit the usefulness and utility of your iPad if you should you ever need reset or restore your iPad. As such, if you want or need to access most current Apps, requiring more recent versions of iOS, you’ll need to consider replacement of your iPad with a newer or current model.

Of current models, even the entry-level iPad8 has specifications and capabilities that will massively outperform you current iPad - and is compatible with the vast majority of current Apps. Other models are more powerful still.

Perhaps you don't have an iPad Mini 2nd generation (it supports iOS version 12.5.1).

Most likely you have an iPad Mini 1st gen, which cannot support iOS versions beyond 9.3.5, because of hardware incompatibility.

Look at the back cover of your iPad and you should find one of these model codes: A1432 or A1454 or A1455.

Regards

Giulio

If it says it can't update farther then there is nothing you can do.

"Update your iPhone, iPad, or iPod touch" --> https://support.apple.com/HT204204 - When you try to update you will only be given one update selection which will be the highest available iOS version supported by your device. If it says the device is up to date and you need a higher OS version you will have to buy newer equipment.

We now await a bunch of other posts telling you in detailed prose what I just told you.