Got this error reported by email:
Illegal length modifier specified 'f' in s[np]printf call in /home/track/vendor/twig/twig/src/Cache/FilesystemCache.php 65 using PHP 7.3.21
in Matomo 3.13.6
@mattab I'll close this for now as we upgraded to a new major twig version in Matomo 4 so this might be fixed. Also we can't fix this ourselves anyway and be best to otherwise create an issue in the twig repository if this happens again in Matomo 4. The sprintf calls look actually good/standard to me.
fyi got another report from a different user Illegal length modifier specified 'f' in s[np]printf call in /home/public_html/vendor/twig/twig/src/Cache/FilesystemCache.php 65 using PHP 7.2.33
see https://stackoverflow.com/questions/61861990/illegal-length-modifier-specified eg switching to PHP 7.4 seems to make the error go away.
I talked a bit about this issue here:
It might be some weird PHP bug where
rename internally call