Overview:
When verifying an Expression Rule from the Network Expression Rules section of the Source Subscription tab, an error appears in the RULE text:
Function 'EXIST' missing or name invalid in expression {EXIST(Field Name)} at 1:7
Root Cause:
The function name is incorrect. In this screenshot, EXIST needs to be replaced by EXISTS.
Solution:
Correct the function name from EXIST to EXISTS.
Related Documentation:
Veeva Network Help: Using rule expressions