We couldn't find a free Diablo process to attach. There are 64bit version(s) of Diabl

[aspendinos]

We couldn't find a free Diablo process to attach. There are 64bit version(s) of Diablo running. Please make sure you start the 32bit client of Diablo.

 

[Touch]

Make sure you lauch Diablo in 32bit version. This can be done in the Battle.net option > Game options > Diablo

 

[Nesox]

Toggling 32-Bit Mode - Blizzard Support