I've recently being unable to upload archives compiled with Xcode9 to itunes connect. The error I'm getting is:
iTunes Store Operation Failed
ERROR ITMS-90512: "Invalid sdk value. The value provided for the sdk portion of \
LC_VERSION_MIN_IPHONEOS in MyApp.app/MyApp is 11.0 which is greater than the \
maximum allowed value of 10.3."
It looks like similar problems were an Apple bug in the past:
ERROR ITMS-90512: Invalid sdk value... 8.2 is higher than maximum allowed value of 10.3?
but it might also be that Xcode 9 should not be used for publishing. However that worked in the past.