Some weeks ago I had some issues with the latest iOS on my WB25 app. After much digging I discovered that when I pressed a button it was trying to execute page synch which was causing an out of synch error - even though the button was AJAX.
I found that if I unclicked this box on the button description - Advanced - Call the page synch......then the problem went away.
Now it's back on the upload control - on the latest iOS I get EXACTLY the same issue - when it executes UploadStart it does a page synch which causes an error. But the upload control doesn't have an option to switch off the page synch.
It's also all to do with the way the page is called that's doing the upload. It gets complicated!
Anyhow, in short I have to call the page using a pagedisplay (in non-ajax mode) from a button that has the above mentioned tick box off. THEN IT WORKS!!!!!! You have no idea how many hours it took to find that out!
