I have gotten that same error after updating the past several versions, but keep forgetting to fix it.
It doesn't hurt anything. This is what is causing it if you are curious:
After update MLV restarts, and reopens any log file you had open when it closed. If you didn't have a file open it tries to open a file named " " and creates an error. This has really been happening all along with Auto Update.
the difference is that somewhere around 2.68 I changed error reporting. In earlier version almost all non critical errors were suppressed and logged, but not reported to the user. So, that error was suppressed by that and wasn't there. Now by default errors are reported to the user unless otherwise handled.
In this case it will probably take less time for me to get rid of that error than it did to explain it, so let me do that before then next release