Same error seen with V5.8.8 ! Is this a regression ? 
The error is seen when I want to choose a file on my local machine.
I use ui vision from 2 years and after more and more tests i suspect this error is when the command execution is slow and ui vision have a delay because try to continue with next command.
I solved IPC error (another type) increasing timeout_wait to 10, with timeout_wait to 1 give the error because the page load slowly from somes iframe internal.
In my opinion this error showed when a command is slow and ui vision try to execute next command.
In my case, I think that it is another problem, because the file path isn’t the one asked on uivision.
The file path asked is this on the capture on my previous message but the file path I see is different and no change is happen…
The file path is blocked into the file path where I have my macro…
I don’t know how to do to resolve this problem, because the delay is to 30 yet…
I have deleted uivision from my navigator and reinstall it, and I have no error anymore…
Mystery…
I’m still facing this issue. Version 6.3.3