[KevinH]

The fact that the empty folders are left behind is in fact indicative of a real problem. They should have been erased when Sigil exited. It is in main.cpp right at the end.

So something is definitely funny. Everything should now be moved to be inside the Sigil Prefs folder.

On Windows is Sigil Prefs in roaming?

They should be appearing inside the QtWebEngine folder right beside where the local-storage and PreviewCache folders are created.

Perhaps we do need to somehow patch Qt on Windows to get the cache path set to be someplace normal.

Either way, something is blocking the clearing of the cache, but they should now be in separate unique folders and no file lock should interfere.

I think you may be right and something in chromium/qtwebengine is creating the caches in one place while trying to clear the cache someplace else.

So very strange.

I am going to try just using unnamed storage and making off-the-record profile for Preview to see if that changes anything. I will push it to master once I get something working.