iPhone upgraded to iOS 11 - retrieve log data from an old incompatible app called "Articles"
There are a couple possibilities.  

You can backup your iPhone using iTunes, and then try restoring your iPhone's backup to another iPhone that is running an older iOS version.

You can backup your iPhone to a Mac using iTunes with encryption turned off, and try using one of the (paid?) Mac utilities that can read unencrypted iOS backup files in the iTunes backup directory.