"Action couldn't be completed" error when you upload a file to a persistent chat room in Skype for Business Server 2015

Symptoms

When you try to upload a file that has no English characters included in the file name to a persistent chat room in a Microsoft Skype for Business Server 2015 environment, other members in the room cannot see the file, and you receive the following error message:

Cause

This issue occurs because the program cannot convert the file name that's encoded by UTF-8.

Resolution

To fix this issue, install the December 2017 cumulative update 6.0.9319.510 for Skype for Business Server 2015, Persistent Chat Server.