I'm using latest github release for Windows and I'm encountering a problem that looks like a bug.
Please let me know if I'm doing something wrong or should this be reported on the bug tracker.
I extracted the feature that causes the problem into a new document and I managed to replicate it there consistently. I'm attaching that document here. It is only a part of a larger model, but shows the problem.
I have a sketch like this:
I have those construction lines there to constrain arcs in a way that doesn't brake when underlying dimensions change. If I simply constrain each arc point and its center this causes a problem described elsewhere. This is my current workaround. I hope it is not what causes the fillet to fail.
Then this is padded by 10mm.
And finally if any of the top edges are selected and chamfer/fillet tool is used the part disappears and an error is shown on the bottom:
14:38:25 Illegal storage access...
14:38:25 <Exception> Illegal storage access! Please save your work under a new file name and restart the application!
It is also on the screenshot below:
Additionally if the whole top face is selected and Chamfer/Fillet is pressed FreeCAD freezes for few seconds and crashes with no message.
This is my freecad version:
OS: Windows 10 (10.0)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.23709 (Git)
Build type: Release
Branch: master
Hash: 625502bb4770e8bb0d3f4eb5e2150fa353c8c7fb
Python version: 3.6.8
Qt version: 5.12.1
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/United States (en_US)