Error compiling a book

[John McWilliam]

Windows 10 Frescobaldi 3.2 Liliypond 2.24.0   I am getting the following error when compiling my book to tunes:   programming error: file name not normalized: ..\..\Includes\Polis_format_portrait.ily continuing, cross fingers   The compilation proceeds successfully and the result appears normal, however, it would be good to eliminate the cause. Can anyone throw light on what this means and how to correct the error.   You will note that my include file is of type “.ily” instead of “.ly” I cannot remember why I did this and it may be of significance.   John McWilliam   Sent from Mail for Windows