Cannot able to activate flow

[Yuvan Raj Kuma1]

Hello Everybody,

 When I try to activate my flow its failing with the below error.Please help me to fix this.

com.glide.flow.model.PharmacyCompound.getPrescription()" because the return value of "java.util.Map.get(Object)" is null

[Josh Barbour]

I had the same message, I found one of the data pills was no longer available so the reference was a sys_id. Once replaced it worked.