Make sure the latest version of iOS version is installed on the iPhone or iPad.
 
Go to Settings on the iPhone, Photos and turn off the iCloud Photos.
 
Open iDiskk Max App and go to: Copy Files -> Copy Photos from iPhone and Select few photos and choose Copy to iDiskk Max to see if they will copy and if the message appears when trying to copy certain files.
 
If the message is displayed when copying certain files or if the app crashes, those files maybe damaged or corrupted which could be causing the message to pop up or casuing the app to crash.
 
Remove the corrupted or damaged files and setup the automatic backup.