I know this is an old post, but I had the same issue, moved everything to become path without spaces in the folder names.
Everything worked afterwards.
Had my project in my documents folder and the IDE iin AC6 folder on root, which as you can see caused the problem.
So the project folder can not have spaces in its path.
Need confirmation through if this is an eclipse issue,which I believe so as my search for such problem returned originally C++ posts about similar error.
One other thing, I realized that my code compiled and uploaded to my STM micro, which is weird since the error was appearing after the upload. Not sure what exactly was happening in the background for this error to appear, which makes sense to investigate further.
I would really appreciate some feedback on this if anyone can elaborate on the inner workings of this.