This probably comes from a recipe which saves some custom page attribute
in the disk file when saving a wiki page.
If you're currently saving a page like Main.MyPage, look with a text
editor at the disk file in wiki.d, either wiki.d/Main.MyPage or in a
subdirectory like wiki.d/Main/Main.MyPage
Having now encountered one bug in the upgrade to PHP 7.4 I'm trying to
check the rest of my recipes out (this is a slow process).
I came across an error that is not immediately related to the inclusion of
a recipe,
PHP Warning: A non-numeric value encountered in
/home/ttcorgnz/public_html/pmwiki
