Q: Pages on iPad

What iOS do you have on y our mini? It's possible if you have an older iOS then you can't update pages (and an update won's show up) until you update.

Try turning Airplane mode on then open a document. If the document opens, go back and turn airplane mode off.

Have you closed Pages, and restarted the device?

Do you use iCloud with Pages? If you do, you could try deleting Pages and then download it again. All of your documents will remain in iCloud even if you delete the app. When you launch the app again, all of your documents will download again.

I Am running out of ideas. Can you create a new document?  Have you tried signing out of your Apple ID, closed all apps, restart the iPad then try again?

Have you tried a forced restart? No data is lost with this procedure. Hold down on the sleep and home buttons at the same time for about 10 seconds until the Apple logo appears on the screen.

I Think you've covered a lot of the bases. the only other thing I can suggest is to try in the iWorks for iOS part of the forum. If some subject matter experts there have anything to suggest?

iWork for iOS

lpoking there some others seem to have the same issue. One other user says they see it sometimes an just keep trying to open the document until it works, so it may simply be a bug with no real fix until APple makes one?

That person specifically mentioned documents started on their Mac not opening on iOS, so maybe a version difference? Or a bug? OR maybe a way to save it on the Mac that makes it more compatible with iOS (yeah I know they should be but stuff happens)

Excellent, I'm happy to hear that it worked for you.