SMSTS.log is a log file that is used for troubleshooting operating system deployment issues and Task Sequence failures in SCCM.smsts.log file. While the TS sequence runs, you can open the smsts.log file by pressing the F8 key. Type CMTrace and you can view the smsts.log file.F8 key and if the command prompt doesn’t appear, it means you haven’t enabled the command support for boot image.