After some indeterminate amount of time (or some unknown event?), I can't open a new Safari window or tab, without getting the message "This webpage was reloaded because a problem occurred" animating down onto the window in an endless loop.
I can reload pages that were already open, and I can browse within a window/tab that was already open, but can't open a new window or tab. Even command-clicking a link from an already-open tab to open that link in a new window results in an empty window, as if I had just opened it (no URL it's trying to load).
I've tried disabling all extensions, but that doesn't help. Ultimately, quitting and relaunching Safari solves it, but then I need to move a bunch of windows across different spaces back where they belong. That's a pain, and I'd rather not have to do that. Any ideas?
I'm on an up-to-date High Sierra (10.13.6), with the stock version of Safari (12.0).