ERROR: cannot infer mimetype from extension for s2member-o.php

After looking at server error logs after getting multiple 503 service unavailable errors I noticed there are a lot of this error:

ERROR: cannot infer mimetype from extension in /public_html/membersfiles/wp-content/plugins/s2member/s2member-o.php

It is getting triggered by multiple pages, have asked my host if it’s something they can look into, but strange how it’s always the same file.

I consider that file to be a sort of canary in the mine. It shows up like this whenever there is a problem on a site, but it’s never the cause.

It sounds like a misconfiguration, either by your host or within a file, that has set the wrong MIME type for a particular type of file. Are you storing files other than those permitted by WP by default?

Hi Tim, thanks for the reply,
Not sure what you mean by ‘storing files’ I got in touch with my host yesterday (Siteground) and was told to check with the plugin devs first to see what, if anything, would need to be changed.

I meant files you have uploaded to WP’s media folder or s2Member’s protected files folder.