Strange errors on windows client

i am using windows10 64bit client v2.6.4stable.
i have nextcloud 17.0.2stable server (ubuntu 18.04) installed locally and the client shows me that it is syncing files from windows to nextcloud server on the linux box, but windows client also
shows some red error messages:

should i be worried? would upgrading to latest server version fix anything?
thanks,
Rod M