ERROR: "Error 10: Incompatibility of type d" in Graphical Query Tool

The following message is displayed when I try to validate a Graphical Query:

"@X3.TRT/SUBALH9$adx (956) Error 10: Incompatibility of type d:
JenkinsSlave
workplace
runtime_Release_release_R095.002
src
afncompi.cpp.1277"

What is causing this error?

X3 displays this sort of error if one or more of the entries in the Selection tab isn't correct. In this case, it was because an entry was

[F:SIH]STA <> '3'

rather than

[F:SIH]STA <> 3

since the STA field is an integer denoting a Local Menu number.

The solution is to change the comparison value to an integer - in this case, 3.