Error log

Dear Autoptimze,

It seems I’m getting an error message in our log which is related to autoptimze:

[Tue Apr 06 15:05:44.284019 2021] [error] [pid 17173] mod_proxy_fcgi.c(871): [client 2a02:1811:ec1f:b300:d8b5:99bd:37f7:41b6:0] AH01071: Got error ‘PHP message: PHP Warning: sprintf(): Too few arguments in /data/sites/web/revivecoachingbe/www/wp-content/plugins/elementor-pro/modules/nav-menu/widgets/nav-menu.php on line 89PHP message: PHP Warning: file_put_contents(): Only -1 of 1548301 bytes written, possibly out of free disk space in /data/sites/web/revivecoachingbe/www/wp-content/plugins/autoptimize/classes/autoptimizeCache.php on line 121’

Any idea what this might be? There seems to be quite some duplicates of this in the error log.
I spotted this after for some reason, the shop page was displayed with almost no CSS. I cleaned the cache of both WP Super Cache and Autoptimze which solved the issue, but I’m still looking for the root-cause.

Thank you in advance for your time!