"rendering device has been lost, application is now closing" error while playing Overwatch (Solved)

1. right click Start & click Windows Power Shell (admin)
2. copy & paste: DISM.exe /Online /Cleanup-image /Restorehealth (Let it run)3. copy & paste: sfc /scannow (Let it run)

This basically is caused by corrupted system files in windows 10. So try System File Checker tool to repair missing or corrupted system files. Full instruction from Microsoft

After the process is finished, you may receive one of the following messages:

Windows Resource Protection did not find any integrity violations.
This means that you do not have any missing or corrupted system files.

Windows Resource Protection could not perform the requested operation.
To resolve this problem, perform the System File Checker scan in safe mode, and make sure that the PendingDeletes and PendingRenames folders exist under %WinDir%\WinSxS\Temp.

Windows Resource Protection found corrupt files and successfully repaired them. 
Details are included in the CBS.Log %WinDir%\Logs\CBS\CBS.log.

To view the detail information about the system file scan and restoration, go to How to view details of the System File Checker process.

Windows Resource Protection found corrupt files but was unable to fix some of them.
Details are included in the CBS.Log %WinDir%\Logs\CBS\CBS.log.