I found a bug (or should I say "unexpected behaviour") that I have in 9.5.1 (I tested pure 9.5.1 and 9.5.1 with HF9 in TM1 Perspectives).
I did not have it in 9.5.
DBR formula returns "#N/A" in Excel when element does not exist in dimension. In 9.5 it used to return "*KEY_ERR".
DBRW returns "*KEY_ERR" both in 9.5 and 9.5.1.
In my case it was useful to look for "*KEY_ERR"s only while doing some validation before sending values to cubes. Now I need additionally to check "#N/A"s.
Regards.