I see you already had this same problem in August 2018:
http://www.lindersoft.com/forums/sho...9460#post89460
http://www.lindersoft.com/forums/sho...9471#post89471
IMO, your issue is caused by a server configuration problem. "Soure file not found" is identical to a typical "404 Page not found" error. This error message is a Hypertext Transfer Protocol (HTTP) standard response code to indicate that the client was able to communicate with the server, but the server could not find what was requested.
Perhaps a typical "load balance configuration" problem.
Friedrich