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:
The action couldn’t be completed. Please try again later.
This issue occurs because the program cannot convert the file name that's encoded by UTF-8.
To fix this issue, install the December 2017 cumulative update 6.0.9319.510 for Skype for Business Server 2015, Persistent Chat Server.