When an Agent won't start, check the log file in the agent\temp folder to see if there's any error.
Symptoms
U02004172 Error while calling function module 'RFC_SYSTEM_INFO'
Initialization of repository destination _E failed: Parameter ABAP application server host ('ashost') is missing
CauseThe Connection Parameter (Remote Function Call tab) of the SAP Connection object is not set up properly
Solution
- Open the SAP Connection object used by your SAP Agent
- Go to Remote Function Call tab
- Enter the missing parameter value (in this case, Application Server)