Entries Keep Showing in The Log

Hi,

I keep getting an entry in the log, sometimes it appears more than once, what does it mean?

{"reqId":"V1DAt5pVP4x3uIJUTvHt","level":0,"time":"2018-02-27T10:25:18+00:00","remoteAddr":"****","user":"--","app":"PHP","method":"PROPFIND","url":"\/nextcloud\/remote.php\/dav\/files\/16454\/","message":"A session had already been started - ignoring session_start() at \/var\/www\/nextcloud\/lib\/private\/Session\/Internal.php#173","userAgent":"Mozilla\/5.0 (Windows) mirall\/2.3.3 (build 1) (Nextcloud)","version":"14.0.0.0"}

also this one, what does it mean

{"reqId":"ubkPR7FdSe3hbO9xUBXB","level":0,"time":"2018-02-27T10:18:43+00:00","remoteAddr":"****","user":"userS","app":"PHP","method":"PUT","url":"\/nextcloud\/remote.php\/dav\/files\/userS\/test\/aaaaaaaaaaaaaaaaaaaa\/wre.txt","message":"rewinddir(): 70 is not a valid Directory resource at \/var\/www\/nextcloud\/3rdparty\/icewind\/streams\/src\/Wrapper.php#31","userAgent":"Mozilla\/5.0 (Windows) mirall\/2.3.3 (build 1) (Nextcloud)","version":"14.0.0.0"}

Thanks