storage setValue error

4.1.4/win/eclipse

on some devices I have an error  when trying save something in storage:

1. in app.onStop() - only in foreground I call app.savedata() (I need func because I need save data in few moments).

2. savedata() is called and inside I try to call STO.setValue() and errors:

A Error Name: System Error (vívoactive® 3 Music: 6.20) - 3 arrays[80] of float (each 415 bytes according to memory monitor), 1 array[20] of float (70bytes) and few integers

B Error Name: File Not Found Error (Forerunner® 945: 9.00) - saving dictionary (a bit complicated)

A - I don't think I exceed any limits

B - system detach storage before onStop()?