The error message was introduced in the Resilio Active Everywhere platform v4.0.0.
The error message appears only on a Windows OS and, in a very specific case, mostly related with the FSLogix use case. Seeing this error message means that the mentioned file got locked (opened in an application) on an Agent while it was downloading the file updated from remote Agents.
To fix that, stop the process that keeps the file open.
Error code SE_FS_FILE_UPDATE_COLLISION