Program &1, include &2: Syntax warning line &3

What causes this issue?

Program <(>&<)>1, include <(>&<)>2: Syntax warning in line <(>&<)>3

System Response

The specified program is not executed.

How to fix this error?

If the log line with the warning text is not yet visible, expand the log
using Expand or Expand All.
To analyze the warning in more detail, check the program in transaction
SE38 with the function Program -> Check. The part of the program with
the error is displayed in the program editor.
Note
A program may contain an error in the transport target system, despite
having functioned correctly in the source system. The reason for this is
the different environment (missing or different include programs or ABAP
Dictionary objects) that the program encounters in the target system.
Check whether the error can be corrected by transporting dependent
objects.

Error message extract from SAP system. Copyright SAP SE.