There is only one report of an error like you are seeing here and the SOLIDWORKS Knowledge Base indicates that it was fixed in 2017 SP1.0. Are you running an earlier version than that?
SPR 953465: SOLIDWORKS Simulation - Dynamic Analysis: File Specific - Getting error message "ERROR IN FILE *.SAF" during linear dynamic study simulation.
Yes, I am running it in 2016 since that is what my customer is using. I will try to run it in 2017.