Q: after updating IOS iPad 2 to version 9.3 it is not possible to activate

There seems to be an issue, especially with older devices. And I would guess that it's on Apple's end since it is affecting so many.

You can try to use iTunes to restore your device from backup

http://support.apple.com/kb/HT1414

Or you could just wait it out and see if Apple fixes things.

This is a known problem/glitch.

Apple, I believe, has acknowledge this issue with activation server difficulties with certain iPad models and have stated that they are working on this issue and that it will be resolved as soon as possible

Here's an recent and additional update.

Apple halts iOS 9.3 updates for older iDevices due to growing Activation Server Lock issues.

WE should all be aware that Apple rarely issues updates that work first time.  I have learnt an important lesson after the v9... Fiasco.

never update immediately- wait for the bugs to be sorted out first!

when are they going to sort out basic problems such as capitalisation of the first word in a paragraph!!!

It's a shame that they have become so incompetent and irresponsible as to release updates that don't work.

The various issues in these forums are the results of the forum software that Apple uses, which is not forum software that is created by Apple.

This forum software is by another software company and it's called Jive.

Apple has no control over the bugs/glitches in this software and they do what we Apple users frequently do.

Wait for the forum software developers to issue updates to their software so Apple can update the software on their end.

Some of the Jive forum software issues are still ongoing, vexing/annoying issues.